From 0de8bef744ee3f21504af3570c690a8f045eead2 Mon Sep 17 00:00:00 2001
From: Michael Goderbauer <goderbauer@google.com>
Date: Mon, 23 Jan 2023 17:36:50 -0800
Subject: [PATCH] Remove unnecessary null checks in flutter/cupertino (#119020)

---
 .../lib/src/cupertino/activity_indicator.dart |  8 +---
 packages/flutter/lib/src/cupertino/app.dart   | 16 +------
 .../lib/src/cupertino/bottom_tab_bar.dart     |  8 +---
 .../flutter/lib/src/cupertino/button.dart     |  4 --
 .../flutter/lib/src/cupertino/colors.dart     | 13 +-----
 .../lib/src/cupertino/context_menu.dart       | 15 +++----
 .../src/cupertino/context_menu_action.dart    |  4 +-
 .../lib/src/cupertino/date_picker.dart        | 16 ++-----
 ...desktop_text_selection_toolbar_button.dart |  6 +--
 .../flutter/lib/src/cupertino/dialog.dart     | 14 +++---
 .../lib/src/cupertino/interface_level.dart    |  5 +--
 .../flutter/lib/src/cupertino/nav_bar.dart    | 35 +++------------
 .../lib/src/cupertino/page_scaffold.dart      |  3 +-
 .../flutter/lib/src/cupertino/picker.dart     | 17 ++------
 .../flutter/lib/src/cupertino/refresh.dart    | 14 ++----
 packages/flutter/lib/src/cupertino/route.dart | 43 ++++---------------
 .../flutter/lib/src/cupertino/scrollbar.dart  |  6 +--
 .../lib/src/cupertino/search_field.dart       |  9 +---
 .../lib/src/cupertino/segmented_control.dart  |  9 +---
 .../flutter/lib/src/cupertino/slider.dart     | 15 ++-----
 .../cupertino/sliding_segmented_control.dart  | 12 +-----
 .../flutter/lib/src/cupertino/switch.dart     | 15 +------
 .../lib/src/cupertino/tab_scaffold.dart       | 23 +++-------
 .../flutter/lib/src/cupertino/tab_view.dart   |  2 +-
 .../flutter/lib/src/cupertino/text_field.dart | 40 ++---------------
 .../src/cupertino/text_form_field_row.dart    | 11 +----
 .../src/cupertino/text_selection_toolbar.dart | 15 ++-----
 .../text_selection_toolbar_button.dart        |  6 +--
 .../flutter/lib/src/cupertino/text_theme.dart |  3 +-
 packages/flutter/lib/src/cupertino/theme.dart | 10 ++---
 .../lib/src/cupertino/thumb_painter.dart      |  2 +-
 31 files changed, 80 insertions(+), 319 deletions(-)

diff --git a/packages/flutter/lib/src/cupertino/activity_indicator.dart b/packages/flutter/lib/src/cupertino/activity_indicator.dart
index 8df6eee0062..bd5bacf6b76 100644
--- a/packages/flutter/lib/src/cupertino/activity_indicator.dart
+++ b/packages/flutter/lib/src/cupertino/activity_indicator.dart
@@ -36,9 +36,7 @@ class CupertinoActivityIndicator extends StatefulWidget {
     this.color,
     this.animating = true,
     this.radius = _kDefaultIndicatorRadius,
-  })  : assert(animating != null),
-        assert(radius != null),
-        assert(radius > 0.0),
+  })  : assert(radius > 0.0),
         progress = 1.0;
 
   /// Creates a non-animated iOS-style activity indicator that displays
@@ -52,9 +50,7 @@ class CupertinoActivityIndicator extends StatefulWidget {
     this.color,
     this.radius = _kDefaultIndicatorRadius,
     this.progress = 1.0,
-  })  : assert(radius != null),
-        assert(radius > 0.0),
-        assert(progress != null),
+  })  : assert(radius > 0.0),
         assert(progress >= 0.0),
         assert(progress <= 1.0),
         animating = false;
diff --git a/packages/flutter/lib/src/cupertino/app.dart b/packages/flutter/lib/src/cupertino/app.dart
index 849c6486814..8aface4f807 100644
--- a/packages/flutter/lib/src/cupertino/app.dart
+++ b/packages/flutter/lib/src/cupertino/app.dart
@@ -177,15 +177,7 @@ class CupertinoApp extends StatefulWidget {
     this.restorationScopeId,
     this.scrollBehavior,
     this.useInheritedMediaQuery = false,
-  }) : assert(routes != null),
-       assert(navigatorObservers != null),
-       assert(title != null),
-       assert(showPerformanceOverlay != null),
-       assert(checkerboardRasterCacheImages != null),
-       assert(checkerboardOffscreenLayers != null),
-       assert(showSemanticsDebugger != null),
-       assert(debugShowCheckedModeBanner != null),
-       routeInformationProvider = null,
+  }) : routeInformationProvider = null,
        routeInformationParser = null,
        routerDelegate = null,
        backButtonDispatcher = null,
@@ -222,12 +214,6 @@ class CupertinoApp extends StatefulWidget {
     this.scrollBehavior,
     this.useInheritedMediaQuery = false,
   }) : assert(routerDelegate != null || routerConfig != null),
-       assert(title != null),
-       assert(showPerformanceOverlay != null),
-       assert(checkerboardRasterCacheImages != null),
-       assert(checkerboardOffscreenLayers != null),
-       assert(showSemanticsDebugger != null),
-       assert(debugShowCheckedModeBanner != null),
        navigatorObservers = null,
        navigatorKey = null,
        onGenerateRoute = null,
diff --git a/packages/flutter/lib/src/cupertino/bottom_tab_bar.dart b/packages/flutter/lib/src/cupertino/bottom_tab_bar.dart
index 5dc70c3665c..209a18a2aa6 100644
--- a/packages/flutter/lib/src/cupertino/bottom_tab_bar.dart
+++ b/packages/flutter/lib/src/cupertino/bottom_tab_bar.dart
@@ -74,16 +74,12 @@ class CupertinoTabBar extends StatelessWidget implements PreferredSizeWidget {
         width: 0.0, // 0.0 means one physical pixel
       ),
     ),
-  }) : assert(items != null),
-       assert(
+  }) : assert(
          items.length >= 2,
          "Tabs need at least 2 items to conform to Apple's HIG",
        ),
-       assert(currentIndex != null),
        assert(0 <= currentIndex && currentIndex < items.length),
-       assert(iconSize != null),
-       assert(height != null && height >= 0.0),
-       assert(inactiveColor != null);
+       assert(height >= 0.0);
 
   /// The interactive items laid out within the bottom navigation bar.
   ///
diff --git a/packages/flutter/lib/src/cupertino/button.dart b/packages/flutter/lib/src/cupertino/button.dart
index 64a5056592d..b5f71d54b9b 100644
--- a/packages/flutter/lib/src/cupertino/button.dart
+++ b/packages/flutter/lib/src/cupertino/button.dart
@@ -50,8 +50,6 @@ class CupertinoButton extends StatefulWidget {
     this.alignment = Alignment.center,
     required this.onPressed,
   }) : assert(pressedOpacity == null || (pressedOpacity >= 0.0 && pressedOpacity <= 1.0)),
-       assert(disabledColor != null),
-       assert(alignment != null),
        _filled = false;
 
   /// Creates an iOS-style button with a filled background.
@@ -71,8 +69,6 @@ class CupertinoButton extends StatefulWidget {
     this.alignment = Alignment.center,
     required this.onPressed,
   }) : assert(pressedOpacity == null || (pressedOpacity >= 0.0 && pressedOpacity <= 1.0)),
-       assert(disabledColor != null),
-       assert(alignment != null),
        color = null,
        _filled = true;
 
diff --git a/packages/flutter/lib/src/cupertino/colors.dart b/packages/flutter/lib/src/cupertino/colors.dart
index 5907e5f8654..18fd90b1098 100644
--- a/packages/flutter/lib/src/cupertino/colors.dart
+++ b/packages/flutter/lib/src/cupertino/colors.dart
@@ -780,16 +780,7 @@ class CupertinoDynamicColor extends Color with Diagnosticable {
     this.darkHighContrastElevatedColor,
     this._debugResolveContext,
     this._debugLabel,
-  ) : assert(color != null),
-      assert(darkColor != null),
-      assert(highContrastColor != null),
-      assert(darkHighContrastColor != null),
-      assert(elevatedColor != null),
-      assert(darkElevatedColor != null),
-      assert(highContrastElevatedColor != null),
-      assert(darkHighContrastElevatedColor != null),
-      assert(_effectiveColor != null),
-      // The super constructor has to be called with a dummy value in order to mark
+  ) : // The super constructor has to be called with a dummy value in order to mark
       // this constructor const.
       // The field `value` is overridden in the class implementation.
       super(0);
@@ -908,7 +899,6 @@ class CupertinoDynamicColor extends Color with Diagnosticable {
   ///  * [maybeResolve], which is similar to this function, but will allow a
   ///    null `resolvable` color.
   static Color resolve(Color resolvable, BuildContext context) {
-    assert(context != null);
     return (resolvable is CupertinoDynamicColor)
       ? resolvable.resolveFrom(context)
       : resolvable;
@@ -931,7 +921,6 @@ class CupertinoDynamicColor extends Color with Diagnosticable {
     if (resolvable == null) {
       return null;
     }
-    assert(context != null);
     return (resolvable is CupertinoDynamicColor)
       ? resolvable.resolveFrom(context)
       : resolvable;
diff --git a/packages/flutter/lib/src/cupertino/context_menu.dart b/packages/flutter/lib/src/cupertino/context_menu.dart
index 5a6024b0936..1545c73b3c6 100644
--- a/packages/flutter/lib/src/cupertino/context_menu.dart
+++ b/packages/flutter/lib/src/cupertino/context_menu.dart
@@ -142,8 +142,7 @@ class CupertinoContextMenu extends StatefulWidget {
       'This feature was deprecated after v3.4.0-34.1.pre.',
     )
     this.previewBuilder = _defaultPreviewBuilder,
-  }) : assert(actions != null && actions.isNotEmpty),
-       assert(child != null),
+  }) : assert(actions.isNotEmpty),
        builder = ((BuildContext context, Animation<double> animation) => child);
 
   /// Creates a context menu with a custom [builder] controlling the widget.
@@ -158,7 +157,7 @@ class CupertinoContextMenu extends StatefulWidget {
     super.key,
     required this.actions,
     required this.builder,
-  }) : assert(actions != null && actions.isNotEmpty),
+  }) : assert(actions.isNotEmpty),
        child = null,
        previewBuilder = null;
 
@@ -794,8 +793,7 @@ class _ContextMenuRoute<T> extends PopupRoute<T> {
     super.filter,
     required Rect previousChildRect,
     super.settings,
-  }) : assert(actions != null && actions.isNotEmpty),
-       assert(contextMenuLocation != null),
+  }) : assert(actions.isNotEmpty),
        _actions = actions,
        _builder = builder,
        _contextMenuLocation = contextMenuLocation,
@@ -1081,8 +1079,7 @@ class _ContextMenuRouteStatic extends StatefulWidget {
     this.onDismiss,
     required this.orientation,
     this.sheetGlobalKey,
-  }) : assert(contextMenuLocation != null),
-       assert(orientation != null);
+  });
 
   final List<Widget>? actions;
   final Widget child;
@@ -1409,9 +1406,7 @@ class _ContextMenuSheet extends StatelessWidget {
     required this.actions,
     required _ContextMenuLocation contextMenuLocation,
     required Orientation orientation,
-  }) : assert(actions != null && actions.isNotEmpty),
-       assert(contextMenuLocation != null),
-       assert(orientation != null),
+  }) : assert(actions.isNotEmpty),
        _contextMenuLocation = contextMenuLocation,
        _orientation = orientation;
 
diff --git a/packages/flutter/lib/src/cupertino/context_menu_action.dart b/packages/flutter/lib/src/cupertino/context_menu_action.dart
index 3cd258becfa..4c26071f2b2 100644
--- a/packages/flutter/lib/src/cupertino/context_menu_action.dart
+++ b/packages/flutter/lib/src/cupertino/context_menu_action.dart
@@ -20,9 +20,7 @@ class CupertinoContextMenuAction extends StatefulWidget {
     this.isDestructiveAction = false,
     this.onPressed,
     this.trailingIcon,
-  }) : assert(child != null),
-       assert(isDefaultAction != null),
-       assert(isDestructiveAction != null);
+  });
 
   /// The widget that will be placed inside the action.
   final Widget child;
diff --git a/packages/flutter/lib/src/cupertino/date_picker.dart b/packages/flutter/lib/src/cupertino/date_picker.dart
index 579ca40105b..d152613729f 100644
--- a/packages/flutter/lib/src/cupertino/date_picker.dart
+++ b/packages/flutter/lib/src/cupertino/date_picker.dart
@@ -81,8 +81,7 @@ class _DatePickerLayoutDelegate extends MultiChildLayoutDelegate {
   _DatePickerLayoutDelegate({
     required this.columnWidths,
     required this.textDirectionFactor,
-  }) : assert(columnWidths != null),
-       assert(textDirectionFactor != null);
+  });
 
   // The list containing widths of all columns.
   final List<double> columnWidths;
@@ -277,14 +276,10 @@ class CupertinoDatePicker extends StatefulWidget {
     this.dateOrder,
     this.backgroundColor,
   }) : initialDateTime = initialDateTime ?? DateTime.now(),
-       assert(mode != null),
-       assert(onDateTimeChanged != null),
-       assert(minimumYear != null),
        assert(
          minuteInterval > 0 && 60 % minuteInterval == 0,
          'minute interval is not a positive integer factor of 60',
        ) {
-    assert(this.initialDateTime != null);
     assert(
       mode != CupertinoDatePickerMode.dateAndTime || minimumDate == null || !this.initialDateTime.isBefore(minimumDate!),
       'initial date is before minimum date',
@@ -944,7 +939,6 @@ class _CupertinoDatePickerDateTimeState extends State<CupertinoDatePicker> {
   }
 
   void _scrollToDate(DateTime newDate, DateTime fromDate, bool minCheck) {
-    assert(newDate != null);
     SchedulerBinding.instance.addPostFrameCallback((Duration timestamp) {
       if (fromDate.year != newDate.year || fromDate.month != newDate.month || fromDate.day != newDate.day) {
         _animateColumnControllerToItem(dateController, selectedDayFromInitial);
@@ -1349,7 +1343,6 @@ class _CupertinoDatePickerDateState extends State<CupertinoDatePicker> {
   }
 
   void _scrollToDate(DateTime newDate) {
-    assert(newDate != null);
     SchedulerBinding.instance.addPostFrameCallback((Duration timestamp) {
       if (selectedYear != newDate.year) {
         _animateColumnControllerToItem(yearController, newDate.year);
@@ -1551,15 +1544,12 @@ class CupertinoTimerPicker extends StatefulWidget {
     this.alignment = Alignment.center,
     this.backgroundColor,
     required this.onTimerDurationChanged,
-  }) : assert(mode != null),
-       assert(onTimerDurationChanged != null),
-       assert(initialTimerDuration >= Duration.zero),
+  }) : assert(initialTimerDuration >= Duration.zero),
        assert(initialTimerDuration < const Duration(days: 1)),
        assert(minuteInterval > 0 && 60 % minuteInterval == 0),
        assert(secondInterval > 0 && 60 % secondInterval == 0),
        assert(initialTimerDuration.inMinutes % minuteInterval == 0),
-       assert(initialTimerDuration.inSeconds % secondInterval == 0),
-       assert(alignment != null);
+       assert(initialTimerDuration.inSeconds % secondInterval == 0);
 
   /// The mode of the timer picker.
   final CupertinoTimerPickerMode mode;
diff --git a/packages/flutter/lib/src/cupertino/desktop_text_selection_toolbar_button.dart b/packages/flutter/lib/src/cupertino/desktop_text_selection_toolbar_button.dart
index b035f622ec8..677530c1340 100644
--- a/packages/flutter/lib/src/cupertino/desktop_text_selection_toolbar_button.dart
+++ b/packages/flutter/lib/src/cupertino/desktop_text_selection_toolbar_button.dart
@@ -37,8 +37,7 @@ class CupertinoDesktopTextSelectionToolbarButton extends StatefulWidget {
     super.key,
     required this.onPressed,
     required Widget this.child,
-  }) : assert(child != null),
-       buttonItem = null;
+  }) : buttonItem = null;
 
   /// Create an instance of [CupertinoDesktopTextSelectionToolbarButton] whose child is
   /// a [Text] widget styled like the default Mac context menu button.
@@ -66,8 +65,7 @@ class CupertinoDesktopTextSelectionToolbarButton extends StatefulWidget {
   CupertinoDesktopTextSelectionToolbarButton.buttonItem({
     super.key,
     required ContextMenuButtonItem this.buttonItem,
-  }) : assert(buttonItem != null),
-       onPressed = buttonItem.onPressed,
+  }) : onPressed = buttonItem.onPressed,
        child = null;
 
   /// {@macro flutter.cupertino.CupertinoTextSelectionToolbarButton.onPressed}
diff --git a/packages/flutter/lib/src/cupertino/dialog.dart b/packages/flutter/lib/src/cupertino/dialog.dart
index 6735f5c5419..4d32891b0e5 100644
--- a/packages/flutter/lib/src/cupertino/dialog.dart
+++ b/packages/flutter/lib/src/cupertino/dialog.dart
@@ -201,7 +201,7 @@ class CupertinoAlertDialog extends StatelessWidget {
     this.actionScrollController,
     this.insetAnimationDuration = const Duration(milliseconds: 100),
     this.insetAnimationCurve = Curves.decelerate,
-  }) : assert(actions != null);
+  });
 
   /// The (optional) title of the dialog is displayed in a large font at the top
   /// of the dialog.
@@ -665,8 +665,7 @@ class CupertinoActionSheetAction extends StatelessWidget {
     this.isDefaultAction = false,
     this.isDestructiveAction = false,
     required this.child,
-  }) : assert(child != null),
-       assert(onPressed != null);
+  });
 
   /// The callback that is called when the button is tapped.
   ///
@@ -701,7 +700,7 @@ class CupertinoActionSheetAction extends StatelessWidget {
     }
 
     return MouseRegion(
-      cursor: onPressed != null && kIsWeb ? SystemMouseCursors.click : MouseCursor.defer,
+      cursor: kIsWeb ? SystemMouseCursors.click : MouseCursor.defer,
       child: GestureDetector(
         onTap: onPressed,
         behavior: HitTestBehavior.opaque,
@@ -896,7 +895,6 @@ class _CupertinoDialogRenderElement extends RenderObjectElement {
   }
 
   void _placeChildInSlot(RenderObject child, _AlertDialogSections slot) {
-    assert(slot != null);
     switch (slot) {
       case _AlertDialogSections.contentSection:
         renderObject.contentSection = child as RenderBox;
@@ -1443,7 +1441,7 @@ class _CupertinoAlertActionSection extends StatelessWidget {
     this.scrollController,
     this.hasCancelButton = false,
     this.isActionSheet = false,
-  }) : assert(children != null);
+  });
 
   final List<Widget> children;
 
@@ -1593,9 +1591,7 @@ class CupertinoDialogAction extends StatelessWidget {
     this.isDestructiveAction = false,
     this.textStyle,
     required this.child,
-  }) : assert(child != null),
-       assert(isDefaultAction != null),
-       assert(isDestructiveAction != null);
+  });
 
   /// The callback that is called when the button is tapped or otherwise
   /// activated.
diff --git a/packages/flutter/lib/src/cupertino/interface_level.dart b/packages/flutter/lib/src/cupertino/interface_level.dart
index 58ffe5fb80b..e4de7829a17 100644
--- a/packages/flutter/lib/src/cupertino/interface_level.dart
+++ b/packages/flutter/lib/src/cupertino/interface_level.dart
@@ -45,8 +45,7 @@ class CupertinoUserInterfaceLevel extends InheritedWidget {
     super.key,
     required CupertinoUserInterfaceLevelData data,
     required super.child,
-  }) : assert(data != null),
-      _data = data;
+  }) : _data = data;
 
   final CupertinoUserInterfaceLevelData _data;
 
@@ -65,7 +64,6 @@ class CupertinoUserInterfaceLevel extends InheritedWidget {
   ///  * [maybeOf], which is similar, but will return null if no
   ///    [CupertinoUserInterfaceLevel] encloses the given context.
   static CupertinoUserInterfaceLevelData of(BuildContext context) {
-    assert(context != null);
     final CupertinoUserInterfaceLevel? query = context.dependOnInheritedWidgetOfExactType<CupertinoUserInterfaceLevel>();
     if (query != null) {
       return query._data;
@@ -95,7 +93,6 @@ class CupertinoUserInterfaceLevel extends InheritedWidget {
   ///  * [of], which is similar, but will throw an exception if no
   ///    [CupertinoUserInterfaceLevel] encloses the given context.
   static CupertinoUserInterfaceLevelData? maybeOf(BuildContext context) {
-    assert(context != null);
     final CupertinoUserInterfaceLevel? query = context.dependOnInheritedWidgetOfExactType<CupertinoUserInterfaceLevel>();
     if (query != null) {
       return query._data;
diff --git a/packages/flutter/lib/src/cupertino/nav_bar.dart b/packages/flutter/lib/src/cupertino/nav_bar.dart
index a1395cdf75f..88bb34b368f 100644
--- a/packages/flutter/lib/src/cupertino/nav_bar.dart
+++ b/packages/flutter/lib/src/cupertino/nav_bar.dart
@@ -257,15 +257,7 @@ class CupertinoNavigationBar extends StatefulWidget implements ObstructingPrefer
     this.padding,
     this.transitionBetweenRoutes = true,
     this.heroTag = _defaultHeroTag,
-  }) : assert(automaticallyImplyLeading != null),
-       assert(automaticallyImplyMiddle != null),
-       assert(transitionBetweenRoutes != null),
-       assert(
-         heroTag != null,
-         'heroTag cannot be null. Use transitionBetweenRoutes = false to '
-         'disable Hero transition on this navigation bar.',
-       ),
-       assert(
+  }) : assert(
          !transitionBetweenRoutes || identical(heroTag, _defaultHeroTag),
          'Cannot specify a heroTag override if this navigation bar does not '
          'transition due to transitionBetweenRoutes = false.',
@@ -599,9 +591,7 @@ class CupertinoSliverNavigationBar extends StatefulWidget {
     this.transitionBetweenRoutes = true,
     this.heroTag = _defaultHeroTag,
     this.stretch = false,
-  }) : assert(automaticallyImplyLeading != null),
-       assert(automaticallyImplyTitle != null),
-       assert(
+  }) : assert(
          automaticallyImplyTitle == true || largeTitle != null,
          'No largeTitle has been provided but automaticallyImplyTitle is also '
          'false. Either provide a largeTitle or set automaticallyImplyTitle to '
@@ -781,9 +771,7 @@ class _LargeTitleNavigationBarSliverDelegate
     required this.persistentHeight,
     required this.alwaysShowMiddle,
     required this.stretchConfiguration,
-  }) : assert(persistentHeight != null),
-       assert(alwaysShowMiddle != null),
-       assert(transitionBetweenRoutes != null);
+  });
 
   final _NavigationBarStaticComponentsKeys keys;
   final _NavigationBarStaticComponents components;
@@ -1626,9 +1614,7 @@ class _TransitionableNavigationBar extends StatelessWidget {
     required this.hasUserMiddle,
     required this.largeExpanded,
     required this.child,
-  }) : assert(componentsKeys != null),
-       assert(largeExpanded != null),
-       assert(!largeExpanded || largeTitleTextStyle != null),
+  }) : assert(!largeExpanded || largeTitleTextStyle != null),
        super(key: componentsKeys.navBarBoxKey);
 
   final _NavigationBarStaticComponentsKeys componentsKeys;
@@ -2100,7 +2086,7 @@ class _NavigationBarComponentsTransition {
       return null;
     }
 
-    if (bottomLargeTitle != null && topBackLabel != null) {
+    if (topBackLabel != null) {
       // Move from current position to the top page's back label position.
       return slideFromLeadingEdge(
         fromKey: bottomComponents.largeTitleKey,
@@ -2127,7 +2113,7 @@ class _NavigationBarComponentsTransition {
       );
     }
 
-    if (bottomLargeTitle != null && topLeading != null) {
+    if (topLeading != null) {
       // Unlike bottom middle, the bottom large title moves when it can't
       // transition to the top back label position.
       final RelativeRect from = positionInTransitionBox(bottomComponents.largeTitleKey, from: bottomNavBarBox);
@@ -2258,7 +2244,6 @@ class _NavigationBarComponentsTransition {
     // text is too long, the topBackLabel will say 'Back' instead of the original
     // text.
     if (bottomLargeTitle != null &&
-        topBackLabel != null &&
         bottomLargeExpanded) {
       return slideFromLeadingEdge(
         fromKey: bottomComponents.largeTitleKey,
@@ -2282,7 +2267,7 @@ class _NavigationBarComponentsTransition {
 
     // The topBackLabel always comes from the large title first if available
     // and expanded instead of middle.
-    if (bottomMiddle != null && topBackLabel != null) {
+    if (bottomMiddle != null) {
       return slideFromLeadingEdge(
         fromKey: bottomComponents.middleKey,
         fromNavBarBox: bottomNavBarBox,
@@ -2452,10 +2437,6 @@ Widget _navBarHeroFlightShuttleBuilder(
   BuildContext fromHeroContext,
   BuildContext toHeroContext,
 ) {
-  assert(animation != null);
-  assert(flightDirection != null);
-  assert(fromHeroContext != null);
-  assert(toHeroContext != null);
   assert(fromHeroContext.widget is Hero);
   assert(toHeroContext.widget is Hero);
 
@@ -2468,8 +2449,6 @@ Widget _navBarHeroFlightShuttleBuilder(
   final _TransitionableNavigationBar fromNavBar = fromHeroWidget.child as _TransitionableNavigationBar;
   final _TransitionableNavigationBar toNavBar = toHeroWidget.child as _TransitionableNavigationBar;
 
-  assert(fromNavBar.componentsKeys != null);
-  assert(toNavBar.componentsKeys != null);
 
   assert(
     fromNavBar.componentsKeys.navBarBoxKey.currentContext!.owner != null,
diff --git a/packages/flutter/lib/src/cupertino/page_scaffold.dart b/packages/flutter/lib/src/cupertino/page_scaffold.dart
index 983cac302c2..db42ae8925f 100644
--- a/packages/flutter/lib/src/cupertino/page_scaffold.dart
+++ b/packages/flutter/lib/src/cupertino/page_scaffold.dart
@@ -39,8 +39,7 @@ class CupertinoPageScaffold extends StatefulWidget {
     this.backgroundColor,
     this.resizeToAvoidBottomInset = true,
     required this.child,
-  }) : assert(child != null),
-       assert(resizeToAvoidBottomInset != null);
+  });
 
   /// The [navigationBar], typically a [CupertinoNavigationBar], is drawn at the
   /// top of the screen.
diff --git a/packages/flutter/lib/src/cupertino/picker.dart b/packages/flutter/lib/src/cupertino/picker.dart
index 232644ed56e..71e23e2dc6f 100644
--- a/packages/flutter/lib/src/cupertino/picker.dart
+++ b/packages/flutter/lib/src/cupertino/picker.dart
@@ -83,13 +83,9 @@ class CupertinoPicker extends StatefulWidget {
     required List<Widget> children,
     this.selectionOverlay = const CupertinoPickerDefaultSelectionOverlay(),
     bool looping = false,
-  }) : assert(children != null),
-       assert(diameterRatio != null),
-       assert(diameterRatio > 0.0, RenderListWheelViewport.diameterRatioZeroMessage),
+  }) : assert(diameterRatio > 0.0, RenderListWheelViewport.diameterRatioZeroMessage),
        assert(magnification > 0),
-       assert(itemExtent != null),
        assert(itemExtent > 0),
-       assert(squeeze != null),
        assert(squeeze > 0),
        childDelegate = looping
                        ? ListWheelChildLoopingListDelegate(children: children)
@@ -126,13 +122,9 @@ class CupertinoPicker extends StatefulWidget {
     required NullableIndexedWidgetBuilder itemBuilder,
     int? childCount,
     this.selectionOverlay = const CupertinoPickerDefaultSelectionOverlay(),
-  }) : assert(itemBuilder != null),
-       assert(diameterRatio != null),
-       assert(diameterRatio > 0.0, RenderListWheelViewport.diameterRatioZeroMessage),
+  }) : assert(diameterRatio > 0.0, RenderListWheelViewport.diameterRatioZeroMessage),
        assert(magnification > 0),
-       assert(itemExtent != null),
        assert(itemExtent > 0),
-       assert(squeeze != null),
        assert(squeeze > 0),
        childDelegate = ListWheelChildBuilderDelegate(builder: itemBuilder, childCount: childCount);
 
@@ -254,7 +246,6 @@ class _CupertinoPickerState extends State<CupertinoPicker> {
         hasSuitableHapticHardware = false;
         break;
     }
-    assert(hasSuitableHapticHardware != null);
     if (hasSuitableHapticHardware && index != _lastHapticIndex) {
       _lastHapticIndex = index;
       HapticFeedback.selectionClick();
@@ -355,9 +346,7 @@ class CupertinoPickerDefaultSelectionOverlay extends StatelessWidget {
     this.background = CupertinoColors.tertiarySystemFill,
     this.capStartEdge = true,
     this.capEndEdge = true,
-  }) : assert(background != null),
-       assert(capStartEdge != null),
-       assert(capEndEdge != null);
+  });
 
   /// Whether to use the default use rounded corners and margin on the start side.
   final bool capStartEdge;
diff --git a/packages/flutter/lib/src/cupertino/refresh.dart b/packages/flutter/lib/src/cupertino/refresh.dart
index d98e516dcbd..b9e528c4366 100644
--- a/packages/flutter/lib/src/cupertino/refresh.dart
+++ b/packages/flutter/lib/src/cupertino/refresh.dart
@@ -20,9 +20,7 @@ class _CupertinoSliverRefresh extends SingleChildRenderObjectWidget {
     this.refreshIndicatorLayoutExtent = 0.0,
     this.hasLayoutExtent = false,
     super.child,
-  }) : assert(refreshIndicatorLayoutExtent != null),
-       assert(refreshIndicatorLayoutExtent >= 0.0),
-       assert(hasLayoutExtent != null);
+  }) : assert(refreshIndicatorLayoutExtent >= 0.0);
 
   // The amount of space the indicator should occupy in the sliver in a
   // resting state when in the refreshing mode.
@@ -61,9 +59,7 @@ class _RenderCupertinoSliverRefresh extends RenderSliver
     required double refreshIndicatorExtent,
     required bool hasLayoutExtent,
     RenderBox? child,
-  }) : assert(refreshIndicatorExtent != null),
-       assert(refreshIndicatorExtent >= 0.0),
-       assert(hasLayoutExtent != null),
+  }) : assert(refreshIndicatorExtent >= 0.0),
        _refreshIndicatorExtent = refreshIndicatorExtent,
        _hasLayoutExtent = hasLayoutExtent {
     this.child = child;
@@ -74,7 +70,6 @@ class _RenderCupertinoSliverRefresh extends RenderSliver
   double get refreshIndicatorLayoutExtent => _refreshIndicatorExtent;
   double _refreshIndicatorExtent;
   set refreshIndicatorLayoutExtent(double value) {
-    assert(value != null);
     assert(value >= 0.0);
     if (value == _refreshIndicatorExtent) {
       return;
@@ -89,7 +84,6 @@ class _RenderCupertinoSliverRefresh extends RenderSliver
   bool get hasLayoutExtent => _hasLayoutExtent;
   bool _hasLayoutExtent;
   set hasLayoutExtent(bool value) {
-    assert(value != null);
     if (value == _hasLayoutExtent) {
       return;
     }
@@ -303,9 +297,7 @@ class CupertinoSliverRefreshControl extends StatefulWidget {
     this.refreshIndicatorExtent = _defaultRefreshIndicatorExtent,
     this.builder = buildRefreshIndicator,
     this.onRefresh,
-  }) : assert(refreshTriggerPullDistance != null),
-       assert(refreshTriggerPullDistance > 0.0),
-       assert(refreshIndicatorExtent != null),
+  }) : assert(refreshTriggerPullDistance > 0.0),
        assert(refreshIndicatorExtent >= 0.0),
        assert(
          refreshTriggerPullDistance >= refreshIndicatorExtent,
diff --git a/packages/flutter/lib/src/cupertino/route.dart b/packages/flutter/lib/src/cupertino/route.dart
index 071e787c352..7ea9976c8f1 100644
--- a/packages/flutter/lib/src/cupertino/route.dart
+++ b/packages/flutter/lib/src/cupertino/route.dart
@@ -225,21 +225,11 @@ mixin CupertinoRouteTransitionMixin<T> on PageRoute<T> {
   @override
   Widget buildPage(BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
     final Widget child = buildContent(context);
-    final Widget result = Semantics(
+    return Semantics(
       scopesRoute: true,
       explicitChildNodes: true,
       child: child,
     );
-    assert(() {
-      if (child == null) {
-        throw FlutterError.fromParts(<DiagnosticsNode>[
-          ErrorSummary('The builder for route "${settings.name}" returned null.'),
-          ErrorDescription('Route builders must never return null.'),
-        ]);
-      }
-      return true;
-    }());
-    return result;
   }
 
   // Called by _CupertinoBackGestureDetector when a pop ("back") drag start
@@ -343,9 +333,7 @@ class CupertinoPageRoute<T> extends PageRoute<T> with CupertinoRouteTransitionMi
     this.maintainState = true,
     super.fullscreenDialog,
     super.allowSnapshotting = true,
-  }) : assert(builder != null),
-       assert(maintainState != null),
-       assert(fullscreenDialog != null) {
+  }) {
     assert(opaque);
   }
 
@@ -373,8 +361,7 @@ class _PageBasedCupertinoPageRoute<T> extends PageRoute<T> with CupertinoRouteTr
   _PageBasedCupertinoPageRoute({
     required CupertinoPage<T> page,
     super.allowSnapshotting = true,
-  }) : assert(page != null),
-       super(settings: page) {
+  }) : super(settings: page) {
     assert(opaque);
   }
 
@@ -424,9 +411,7 @@ class CupertinoPage<T> extends Page<T> {
     super.name,
     super.arguments,
     super.restorationId,
-  }) : assert(child != null),
-       assert(maintainState != null),
-       assert(fullscreenDialog != null);
+  });
 
   /// The content to be shown in the [Route] created by this page.
   final Widget child;
@@ -468,8 +453,7 @@ class CupertinoPageTransition extends StatelessWidget {
     required Animation<double> secondaryRouteAnimation,
     required this.child,
     required bool linearTransition,
-  }) : assert(linearTransition != null),
-       _primaryPositionAnimation =
+  }) : _primaryPositionAnimation =
            (linearTransition
              ? primaryRouteAnimation
              : CurvedAnimation(
@@ -607,9 +591,7 @@ class _CupertinoBackGestureDetector<T> extends StatefulWidget {
     required this.enabledCallback,
     required this.onStartPopGesture,
     required this.child,
-  }) : assert(enabledCallback != null),
-       assert(onStartPopGesture != null),
-       assert(child != null);
+  });
 
   final Widget child;
 
@@ -731,8 +713,7 @@ class _CupertinoBackGestureController<T> {
   _CupertinoBackGestureController({
     required this.navigator,
     required this.controller,
-  }) : assert(navigator != null),
-       assert(controller != null) {
+  }) {
     navigator.didStartUserGesture();
   }
 
@@ -854,7 +835,6 @@ class _CupertinoEdgeShadowDecoration extends Decoration {
     _CupertinoEdgeShadowDecoration? b,
     double t,
   ) {
-    assert(t != null);
     if (a == null && b == null) {
       return null;
     }
@@ -921,8 +901,7 @@ class _CupertinoEdgeShadowPainter extends BoxPainter {
   _CupertinoEdgeShadowPainter(
     this._decoration,
     super.onChange,
-  ) : assert(_decoration != null),
-      assert(_decoration._colors == null || _decoration._colors!.length > 1);
+  ) : assert(_decoration._colors == null || _decoration._colors!.length > 1);
 
   final _CupertinoEdgeShadowDecoration _decoration;
 
@@ -1192,7 +1171,6 @@ Future<T?> showCupertinoModalPopup<T>({
   RouteSettings? routeSettings,
   Offset? anchorPoint,
 }) {
-  assert(useRootNavigator != null);
   return Navigator.of(context, rootNavigator: useRootNavigator).push(
     CupertinoModalPopupRoute<T>(
       builder: builder,
@@ -1297,8 +1275,6 @@ Future<T?> showCupertinoDialog<T>({
   RouteSettings? routeSettings,
   Offset? anchorPoint,
 }) {
-  assert(builder != null);
-  assert(useRootNavigator != null);
 
   return Navigator.of(context, rootNavigator: useRootNavigator).push<T>(CupertinoDialogRoute<T>(
     builder: builder,
@@ -1361,8 +1337,7 @@ class CupertinoDialogRoute<T> extends RawDialogRoute<T> {
     super.transitionBuilder = _buildCupertinoDialogTransitions,
     super.settings,
     super.anchorPoint,
-  }) : assert(barrierDismissible != null),
-      super(
+  }) : super(
         pageBuilder: (BuildContext context, Animation<double> animation, Animation<double> secondaryAnimation) {
           return builder(context);
         },
diff --git a/packages/flutter/lib/src/cupertino/scrollbar.dart b/packages/flutter/lib/src/cupertino/scrollbar.dart
index 1b847f24991..42856ca8406 100644
--- a/packages/flutter/lib/src/cupertino/scrollbar.dart
+++ b/packages/flutter/lib/src/cupertino/scrollbar.dart
@@ -87,12 +87,8 @@ class CupertinoScrollbar extends RawScrollbar {
       'This feature was deprecated after v2.9.0-1.0.pre.',
     )
     bool? isAlwaysShown,
-  }) : assert(thickness != null),
-       assert(thickness < double.infinity),
-       assert(thicknessWhileDragging != null),
+  }) : assert(thickness < double.infinity),
        assert(thicknessWhileDragging < double.infinity),
-       assert(radius != null),
-       assert(radiusWhileDragging != null),
        assert(
          isAlwaysShown == null || thumbVisibility == null,
          'Scrollbar thumb appearance should only be controlled with thumbVisibility, '
diff --git a/packages/flutter/lib/src/cupertino/search_field.dart b/packages/flutter/lib/src/cupertino/search_field.dart
index cc876fdbb24..348132406f1 100644
--- a/packages/flutter/lib/src/cupertino/search_field.dart
+++ b/packages/flutter/lib/src/cupertino/search_field.dart
@@ -126,14 +126,7 @@ class CupertinoSearchTextField extends StatefulWidget {
     this.onTap,
     this.autocorrect = true,
     this.enabled,
-  })  : assert(padding != null),
-        assert(itemColor != null),
-        assert(itemSize != null),
-        assert(prefixInsets != null),
-        assert(suffixInsets != null),
-        assert(suffixIcon != null),
-        assert(suffixMode != null),
-        assert(
+  })  : assert(
           !((decoration != null) && (backgroundColor != null)),
           'Cannot provide both a background color and a decoration\n'
           'To provide both, use "decoration: BoxDecoration(color: '
diff --git a/packages/flutter/lib/src/cupertino/segmented_control.dart b/packages/flutter/lib/src/cupertino/segmented_control.dart
index d381128d927..aedd6468119 100644
--- a/packages/flutter/lib/src/cupertino/segmented_control.dart
+++ b/packages/flutter/lib/src/cupertino/segmented_control.dart
@@ -99,9 +99,7 @@ class CupertinoSegmentedControl<T extends Object> extends StatefulWidget {
     this.borderColor,
     this.pressedColor,
     this.padding,
-  }) : assert(children != null),
-       assert(children.length >= 2),
-       assert(onValueChanged != null),
+  }) : assert(children.length >= 2),
        assert(
          groupValue == null || children.keys.any((T child) => child == groupValue),
          'The groupValue must be either null or one of the keys in the children map.',
@@ -458,8 +456,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     required TextDirection textDirection,
     required List<Color> backgroundColors,
     required Color borderColor,
-  }) : assert(textDirection != null),
-       _textDirection = textDirection,
+  }) : _textDirection = textDirection,
        _selectedIndex = selectedIndex,
        _pressedIndex = pressedIndex,
        _backgroundColors = backgroundColors,
@@ -685,7 +682,6 @@ class _RenderSegmentedControl<T> extends RenderBox
   }
 
   void _paintChild(PaintingContext context, Offset offset, RenderBox child, int childIndex) {
-    assert(child != null);
 
     final _SegmentedControlContainerBoxParentData childParentData = child.parentData! as _SegmentedControlContainerBoxParentData;
 
@@ -708,7 +704,6 @@ class _RenderSegmentedControl<T> extends RenderBox
 
   @override
   bool hitTestChildren(BoxHitTestResult result, { required Offset position }) {
-    assert(position != null);
     RenderBox? child = lastChild;
     while (child != null) {
       final _SegmentedControlContainerBoxParentData childParentData = child.parentData! as _SegmentedControlContainerBoxParentData;
diff --git a/packages/flutter/lib/src/cupertino/slider.dart b/packages/flutter/lib/src/cupertino/slider.dart
index 768ccbfe9a8..73a4b523cc8 100644
--- a/packages/flutter/lib/src/cupertino/slider.dart
+++ b/packages/flutter/lib/src/cupertino/slider.dart
@@ -71,12 +71,8 @@ class CupertinoSlider extends StatefulWidget {
     this.divisions,
     this.activeColor,
     this.thumbColor = CupertinoColors.white,
-  }) : assert(value != null),
-       assert(min != null),
-       assert(max != null),
-       assert(value >= min && value <= max),
-       assert(divisions == null || divisions > 0),
-       assert(thumbColor != null);
+  }) : assert(value >= min && value <= max),
+       assert(divisions == null || divisions > 0);
 
   /// The currently selected value for this slider.
   ///
@@ -337,9 +333,7 @@ class _RenderCupertinoSlider extends RenderConstrainedBox implements MouseTracke
     required TickerProvider vsync,
     required TextDirection textDirection,
     MouseCursor cursor = MouseCursor.defer,
-  }) : assert(value != null && value >= 0.0 && value <= 1.0),
-       assert(textDirection != null),
-       assert(cursor != null),
+  }) : assert(value >= 0.0 && value <= 1.0),
        _cursor = cursor,
        _value = value,
        _divisions = divisions,
@@ -363,7 +357,7 @@ class _RenderCupertinoSlider extends RenderConstrainedBox implements MouseTracke
   double get value => _value;
   double _value;
   set value(double newValue) {
-    assert(newValue != null && newValue >= 0.0 && newValue <= 1.0);
+    assert(newValue >= 0.0 && newValue <= 1.0);
     if (newValue == _value) {
       return;
     }
@@ -435,7 +429,6 @@ class _RenderCupertinoSlider extends RenderConstrainedBox implements MouseTracke
   TextDirection get textDirection => _textDirection;
   TextDirection _textDirection;
   set textDirection(TextDirection value) {
-    assert(value != null);
     if (_textDirection == value) {
       return;
     }
diff --git a/packages/flutter/lib/src/cupertino/sliding_segmented_control.dart b/packages/flutter/lib/src/cupertino/sliding_segmented_control.dart
index ab3be16440e..2c9365722be 100644
--- a/packages/flutter/lib/src/cupertino/sliding_segmented_control.dart
+++ b/packages/flutter/lib/src/cupertino/sliding_segmented_control.dart
@@ -320,10 +320,7 @@ class CupertinoSlidingSegmentedControl<T> extends StatefulWidget {
     this.thumbColor = _kThumbColor,
     this.padding = _kHorizontalItemPadding,
     this.backgroundColor = CupertinoColors.tertiarySystemFill,
-  }) : assert(children != null),
-       assert(children.length >= 2),
-       assert(padding != null),
-       assert(onValueChanged != null),
+  }) : assert(children.length >= 2),
        assert(
          groupValue == null || children.keys.contains(groupValue),
          'The groupValue must be either null or one of the keys in the children map.',
@@ -523,7 +520,6 @@ class _SegmentedControlState<T> extends State<CupertinoSlidingSegmentedControl<T
   // _Segment widget) to make the overall animation look natural when the thumb
   // is not sliding.
   void _playThumbScaleAnimation({ required bool isExpanding }) {
-    assert(isExpanding != null);
     thumbScaleAnimation = thumbScaleController.drive(
       Tween<double>(
         begin: thumbScaleAnimation.value,
@@ -793,8 +789,7 @@ class _RenderSegmentedControl<T> extends RenderBox
     required this.state,
   }) : _highlightedIndex = highlightedIndex,
        _thumbColor = thumbColor,
-       _thumbScale = thumbScale,
-       assert(state != null);
+       _thumbScale = thumbScale;
 
   final _SegmentedControlState<T> state;
 
@@ -1074,13 +1069,11 @@ class _RenderSegmentedControl<T> extends RenderBox
   // Paint the separator to the right of the given child.
   final Paint separatorPaint = Paint();
   void _paintSeparator(PaintingContext context, Offset offset, RenderBox child) {
-    assert(child != null);
     final _SegmentedControlContainerBoxParentData childParentData = child.parentData! as _SegmentedControlContainerBoxParentData;
     context.paintChild(child, offset + childParentData.offset);
   }
 
   void _paintChild(PaintingContext context, Offset offset, RenderBox child) {
-    assert(child != null);
     final _SegmentedControlContainerBoxParentData childParentData = child.parentData! as _SegmentedControlContainerBoxParentData;
     context.paintChild(child, childParentData.offset + offset);
   }
@@ -1119,7 +1112,6 @@ class _RenderSegmentedControl<T> extends RenderBox
 
   @override
   bool hitTestChildren(BoxHitTestResult result, { required Offset position }) {
-    assert(position != null);
     RenderBox? child = lastChild;
     while (child != null) {
       final _SegmentedControlContainerBoxParentData childParentData =
diff --git a/packages/flutter/lib/src/cupertino/switch.dart b/packages/flutter/lib/src/cupertino/switch.dart
index 095a3285aba..e7d5a27de70 100644
--- a/packages/flutter/lib/src/cupertino/switch.dart
+++ b/packages/flutter/lib/src/cupertino/switch.dart
@@ -76,8 +76,7 @@ class CupertinoSwitch extends StatefulWidget {
     this.applyTheme,
     this.focusColor,
     this.dragStartBehavior = DragStartBehavior.start,
-  }) : assert(value != null),
-       assert(dragStartBehavior != null);
+  });
 
   /// Whether this switch is on or off.
   ///
@@ -473,10 +472,7 @@ class _RenderCupertinoSwitch extends RenderConstrainedBox {
     required TextDirection textDirection,
     required bool isFocused,
     required _CupertinoSwitchState state,
-  }) : assert(value != null),
-       assert(activeColor != null),
-       assert(state != null),
-       _value = value,
+  }) : _value = value,
        _activeColor = activeColor,
        _trackColor = trackColor,
        _focusColor = focusColor,
@@ -495,7 +491,6 @@ class _RenderCupertinoSwitch extends RenderConstrainedBox {
   bool get value => _value;
   bool _value;
   set value(bool value) {
-    assert(value != null);
     if (value == _value) {
       return;
     }
@@ -506,7 +501,6 @@ class _RenderCupertinoSwitch extends RenderConstrainedBox {
   Color get activeColor => _activeColor;
   Color _activeColor;
   set activeColor(Color value) {
-    assert(value != null);
     if (value == _activeColor) {
       return;
     }
@@ -517,7 +511,6 @@ class _RenderCupertinoSwitch extends RenderConstrainedBox {
   Color get trackColor => _trackColor;
   Color _trackColor;
   set trackColor(Color value) {
-    assert(value != null);
     if (value == _trackColor) {
       return;
     }
@@ -528,7 +521,6 @@ class _RenderCupertinoSwitch extends RenderConstrainedBox {
   Color get thumbColor => _thumbPainter.color;
   CupertinoThumbPainter _thumbPainter;
   set thumbColor(Color value) {
-    assert(value != null);
     if (value == thumbColor) {
       return;
     }
@@ -539,7 +531,6 @@ class _RenderCupertinoSwitch extends RenderConstrainedBox {
   Color get focusColor => _focusColor;
   Color _focusColor;
   set focusColor(Color value) {
-    assert(value != null);
     if (value == _focusColor) {
       return;
     }
@@ -564,7 +555,6 @@ class _RenderCupertinoSwitch extends RenderConstrainedBox {
   TextDirection get textDirection => _textDirection;
   TextDirection _textDirection;
   set textDirection(TextDirection value) {
-    assert(value != null);
     if (_textDirection == value) {
       return;
     }
@@ -575,7 +565,6 @@ class _RenderCupertinoSwitch extends RenderConstrainedBox {
   bool get isFocused => _isFocused;
   bool _isFocused;
   set isFocused(bool value) {
-    assert(value != null);
     if(value == _isFocused) {
       return;
     }
diff --git a/packages/flutter/lib/src/cupertino/tab_scaffold.dart b/packages/flutter/lib/src/cupertino/tab_scaffold.dart
index 509d3e272ca..056cf18ef96 100644
--- a/packages/flutter/lib/src/cupertino/tab_scaffold.dart
+++ b/packages/flutter/lib/src/cupertino/tab_scaffold.dart
@@ -36,7 +36,6 @@ class CupertinoTabController extends ChangeNotifier {
   /// greater than or equal to 0, and less than the total number of tabs.
   CupertinoTabController({ int initialIndex = 0 })
     : _index = initialIndex,
-      assert(initialIndex != null),
       assert(initialIndex >= 0);
 
   bool _isDisposed = false;
@@ -52,7 +51,6 @@ class CupertinoTabController extends ChangeNotifier {
   int get index => _index;
   int _index;
   set index(int value) {
-    assert(value != null);
     assert(value >= 0);
     if (_index == value) {
       return;
@@ -135,9 +133,7 @@ class CupertinoTabScaffold extends StatefulWidget {
     this.backgroundColor,
     this.resizeToAvoidBottomInset = true,
     this.restorationId,
-  }) : assert(tabBar != null),
-       assert(tabBuilder != null),
-       assert(
+  }) : assert(
          controller == null || controller.index < tabBar.items.length,
          "The CupertinoTabController's current index ${controller.index} is "
          'out of bounds for the tab bar with ${tabBar.items.length} tabs',
@@ -324,12 +320,10 @@ class _CupertinoTabScaffoldState extends State<CupertinoTabScaffold> with Restor
       contentPadding = EdgeInsets.only(bottom: existingMediaQuery.viewInsets.bottom);
     }
 
-    if (widget.tabBar != null &&
-        // Only pad the content with the height of the tab bar if the tab
-        // isn't already entirely obstructed by a keyboard or other view insets.
-        // Don't double pad.
-        (!widget.resizeToAvoidBottomInset ||
-            widget.tabBar.preferredSize.height > existingMediaQuery.viewInsets.bottom)) {
+    // Only pad the content with the height of the tab bar if the tab
+    // isn't already entirely obstructed by a keyboard or other view insets.
+    // Don't double pad.
+    if (!widget.resizeToAvoidBottomInset || widget.tabBar.preferredSize.height > existingMediaQuery.viewInsets.bottom) {
       // TODO(xster): Use real size after partial layout instead of preferred size.
       // https://github.com/flutter/flutter/issues/12912
       final double bottomPadding =
@@ -406,9 +400,7 @@ class _TabSwitchingView extends StatefulWidget {
     required this.currentTabIndex,
     required this.tabCount,
     required this.tabBuilder,
-  }) : assert(currentTabIndex != null),
-       assert(tabCount != null && tabCount > 0),
-       assert(tabBuilder != null);
+  }) : assert(tabCount > 0);
 
   final int currentTabIndex;
   final int tabCount;
@@ -530,8 +522,7 @@ class RestorableCupertinoTabController extends RestorableChangeNotifier<Cupertin
   /// The `initialIndex` must not be null and defaults to 0. The value must be
   /// greater than or equal to 0, and less than the total number of tabs.
   RestorableCupertinoTabController({ int initialIndex = 0 })
-    : assert(initialIndex != null),
-      assert(initialIndex >= 0),
+    : assert(initialIndex >= 0),
       _initialIndex = initialIndex;
 
   final int _initialIndex;
diff --git a/packages/flutter/lib/src/cupertino/tab_view.dart b/packages/flutter/lib/src/cupertino/tab_view.dart
index 3d5948a9c1b..0d8c70a3cbc 100644
--- a/packages/flutter/lib/src/cupertino/tab_view.dart
+++ b/packages/flutter/lib/src/cupertino/tab_view.dart
@@ -50,7 +50,7 @@ class CupertinoTabView extends StatefulWidget {
     this.onUnknownRoute,
     this.navigatorObservers = const <NavigatorObserver>[],
     this.restorationScopeId,
-  }) : assert(navigatorObservers != null);
+  });
 
   /// The widget builder for the default route of the tab view
   /// ([Navigator.defaultRouteName], which is `/`).
diff --git a/packages/flutter/lib/src/cupertino/text_field.dart b/packages/flutter/lib/src/cupertino/text_field.dart
index 72508e3d02b..98ab4ccbdaa 100644
--- a/packages/flutter/lib/src/cupertino/text_field.dart
+++ b/packages/flutter/lib/src/cupertino/text_field.dart
@@ -281,35 +281,21 @@ class CupertinoTextField extends StatefulWidget {
     this.contextMenuBuilder = _defaultContextMenuBuilder,
     this.spellCheckConfiguration,
     this.magnifierConfiguration,
-  }) : assert(textAlign != null),
-       assert(readOnly != null),
-       assert(autofocus != null),
-       assert(obscuringCharacter != null && obscuringCharacter.length == 1),
-       assert(obscureText != null),
-       assert(autocorrect != null),
+  }) : assert(obscuringCharacter.length == 1),
        smartDashesType = smartDashesType ?? (obscureText ? SmartDashesType.disabled : SmartDashesType.enabled),
        smartQuotesType = smartQuotesType ?? (obscureText ? SmartQuotesType.disabled : SmartQuotesType.enabled),
-       assert(enableSuggestions != null),
-       assert(scrollPadding != null),
-       assert(dragStartBehavior != null),
-       assert(selectionHeightStyle != null),
-       assert(selectionWidthStyle != null),
        assert(maxLines == null || maxLines > 0),
        assert(minLines == null || minLines > 0),
        assert(
          (maxLines == null) || (minLines == null) || (maxLines >= minLines),
          "minLines can't be greater than maxLines",
        ),
-       assert(expands != null),
        assert(
          !expands || (maxLines == null && minLines == null),
          'minLines and maxLines must be null when expands is true.',
        ),
        assert(!obscureText || maxLines == 1, 'Obscured fields cannot be multiline.'),
        assert(maxLength == null || maxLength > 0),
-       assert(clearButtonMode != null),
-       assert(prefixMode != null),
-       assert(suffixMode != null),
        // Assert the following instead of setting it directly to avoid surprising the user by silently changing the value they set.
        assert(
          !identical(textInputAction, TextInputAction.newline) ||
@@ -317,7 +303,6 @@ class CupertinoTextField extends StatefulWidget {
          !identical(keyboardType, TextInputType.text),
          'Use keyboardType TextInputType.multiline when using TextInputAction.newline on a multiline TextField.',
        ),
-       assert(enableIMEPersonalizedLearning != null),
        keyboardType = keyboardType ?? (maxLines == 1 ? TextInputType.text : TextInputType.multiline),
        enableInteractiveSelection = enableInteractiveSelection ?? (!readOnly || !obscureText);
 
@@ -425,35 +410,21 @@ class CupertinoTextField extends StatefulWidget {
     this.contextMenuBuilder = _defaultContextMenuBuilder,
     this.spellCheckConfiguration,
     this.magnifierConfiguration,
-  }) : assert(textAlign != null),
-       assert(readOnly != null),
-       assert(autofocus != null),
-       assert(obscuringCharacter != null && obscuringCharacter.length == 1),
-       assert(obscureText != null),
-       assert(autocorrect != null),
+  }) : assert(obscuringCharacter.length == 1),
        smartDashesType = smartDashesType ?? (obscureText ? SmartDashesType.disabled : SmartDashesType.enabled),
        smartQuotesType = smartQuotesType ?? (obscureText ? SmartQuotesType.disabled : SmartQuotesType.enabled),
-       assert(enableSuggestions != null),
-       assert(scrollPadding != null),
-       assert(dragStartBehavior != null),
-       assert(selectionHeightStyle != null),
-       assert(selectionWidthStyle != null),
        assert(maxLines == null || maxLines > 0),
        assert(minLines == null || minLines > 0),
        assert(
          (maxLines == null) || (minLines == null) || (maxLines >= minLines),
          "minLines can't be greater than maxLines",
        ),
-       assert(expands != null),
        assert(
          !expands || (maxLines == null && minLines == null),
          'minLines and maxLines must be null when expands is true.',
        ),
        assert(!obscureText || maxLines == 1, 'Obscured fields cannot be multiline.'),
        assert(maxLength == null || maxLength > 0),
-       assert(clearButtonMode != null),
-       assert(prefixMode != null),
-       assert(suffixMode != null),
        // Assert the following instead of setting it directly to avoid surprising the user by silently changing the value they set.
        assert(
          !identical(textInputAction, TextInputAction.newline) ||
@@ -461,8 +432,6 @@ class CupertinoTextField extends StatefulWidget {
          !identical(keyboardType, TextInputType.text),
          'Use keyboardType TextInputType.multiline when using TextInputAction.newline on a multiline TextField.',
        ),
-       assert(clipBehavior != null),
-       assert(enableIMEPersonalizedLearning != null),
        keyboardType = keyboardType ?? (maxLines == 1 ? TextInputType.text : TextInputType.multiline),
        enableInteractiveSelection = enableInteractiveSelection ?? (!readOnly || !obscureText);
 
@@ -1102,9 +1071,6 @@ class _CupertinoTextFieldState extends State<CupertinoTextField> with Restoratio
   }
 
   Widget _addTextDependentAttachments(Widget editableText, TextStyle textStyle, TextStyle placeholderStyle) {
-    assert(editableText != null);
-    assert(textStyle != null);
-    assert(placeholderStyle != null);
     // If there are no surrounding widgets, just return the core editable text
     // part.
     if (!_hasDecoration) {
@@ -1267,7 +1233,7 @@ class _CupertinoTextFieldState extends State<CupertinoTextField> with Restoratio
           ? side
           : side.copyWith(color: CupertinoDynamicColor.resolve(side.color, context));
       }
-      resolvedBorder = border == null || border.runtimeType != Border
+      resolvedBorder = border.runtimeType != Border
         ? border
         : Border(
           top: resolveBorderSide(border.top),
diff --git a/packages/flutter/lib/src/cupertino/text_form_field_row.dart b/packages/flutter/lib/src/cupertino/text_form_field_row.dart
index 9a8ca8600fb..268d8c06125 100644
--- a/packages/flutter/lib/src/cupertino/text_form_field_row.dart
+++ b/packages/flutter/lib/src/cupertino/text_form_field_row.dart
@@ -158,28 +158,19 @@ class CupertinoTextFormFieldRow extends FormField<String> {
     ),
     EditableTextContextMenuBuilder? contextMenuBuilder = _defaultContextMenuBuilder,
   })  : assert(initialValue == null || controller == null),
-        assert(textAlign != null),
-        assert(autofocus != null),
-        assert(readOnly != null),
-        assert(obscuringCharacter != null && obscuringCharacter.length == 1),
-        assert(obscureText != null),
-        assert(autocorrect != null),
-        assert(enableSuggestions != null),
-        assert(scrollPadding != null),
+        assert(obscuringCharacter.length == 1),
         assert(maxLines == null || maxLines > 0),
         assert(minLines == null || minLines > 0),
         assert(
           (maxLines == null) || (minLines == null) || (maxLines >= minLines),
           "minLines can't be greater than maxLines",
         ),
-        assert(expands != null),
         assert(
           !expands || (maxLines == null && minLines == null),
           'minLines and maxLines must be null when expands is true.',
         ),
         assert(!obscureText || maxLines == 1, 'Obscured fields cannot be multiline.'),
         assert(maxLength == null || maxLength > 0),
-        assert(enableInteractiveSelection != null),
         super(
           initialValue: controller?.text ?? initialValue ?? '',
           builder: (FormFieldState<String> field) {
diff --git a/packages/flutter/lib/src/cupertino/text_selection_toolbar.dart b/packages/flutter/lib/src/cupertino/text_selection_toolbar.dart
index 9537dfedd02..bee18a8648a 100644
--- a/packages/flutter/lib/src/cupertino/text_selection_toolbar.dart
+++ b/packages/flutter/lib/src/cupertino/text_selection_toolbar.dart
@@ -426,8 +426,7 @@ class _CupertinoTextSelectionToolbarContent extends StatefulWidget {
     required this.isAbove,
     required this.toolbarBuilder,
     required this.children,
-  }) : assert(children != null),
-       assert(children.length > 0);
+  }) : assert(children.length > 0);
 
   final Offset anchor;
   final List<Widget> children;
@@ -533,13 +532,7 @@ class _CupertinoTextSelectionToolbarItems extends RenderObjectWidget {
     required this.dividerWidth,
     required this.nextButton,
     required this.nextButtonDisabled,
-  }) : assert(children != null),
-       assert(children.isNotEmpty),
-       assert(backButton != null),
-       assert(dividerWidth != null),
-       assert(nextButton != null),
-       assert(nextButtonDisabled != null),
-       assert(page != null);
+  }) : assert(children.isNotEmpty);
 
   final Widget backButton;
   final List<Widget> children;
@@ -732,9 +725,7 @@ class _RenderCupertinoTextSelectionToolbarItems extends RenderBox with Container
   _RenderCupertinoTextSelectionToolbarItems({
     required double dividerWidth,
     required int page,
-  }) : assert(dividerWidth != null),
-       assert(page != null),
-       _dividerWidth = dividerWidth,
+  }) : _dividerWidth = dividerWidth,
        _page = page,
        super();
 
diff --git a/packages/flutter/lib/src/cupertino/text_selection_toolbar_button.dart b/packages/flutter/lib/src/cupertino/text_selection_toolbar_button.dart
index 389d65c7e52..aa0550ec911 100644
--- a/packages/flutter/lib/src/cupertino/text_selection_toolbar_button.dart
+++ b/packages/flutter/lib/src/cupertino/text_selection_toolbar_button.dart
@@ -42,8 +42,7 @@ class CupertinoTextSelectionToolbarButton extends StatelessWidget {
     super.key,
     this.onPressed,
     required Widget this.child,
-  }) : assert(child != null),
-       text = null,
+  }) : text = null,
        buttonItem = null;
 
   /// Create an instance of [CupertinoTextSelectionToolbarButton] whose child is
@@ -62,8 +61,7 @@ class CupertinoTextSelectionToolbarButton extends StatelessWidget {
   CupertinoTextSelectionToolbarButton.buttonItem({
     super.key,
     required ContextMenuButtonItem this.buttonItem,
-  }) : assert(buttonItem != null),
-       child = null,
+  }) : child = null,
        text = null,
        onPressed = buttonItem.onPressed;
 
diff --git a/packages/flutter/lib/src/cupertino/text_theme.dart b/packages/flutter/lib/src/cupertino/text_theme.dart
index 2ea7fecb0d4..33f797bae5c 100644
--- a/packages/flutter/lib/src/cupertino/text_theme.dart
+++ b/packages/flutter/lib/src/cupertino/text_theme.dart
@@ -268,8 +268,7 @@ class _TextThemeDefaultsBuilder {
   const _TextThemeDefaultsBuilder(
     this.labelColor,
     this.inactiveGrayColor,
-  ) : assert(labelColor != null),
-      assert(inactiveGrayColor != null);
+  );
 
   final Color labelColor;
   final Color inactiveGrayColor;
diff --git a/packages/flutter/lib/src/cupertino/theme.dart b/packages/flutter/lib/src/cupertino/theme.dart
index 57e08042109..39048b35431 100644
--- a/packages/flutter/lib/src/cupertino/theme.dart
+++ b/packages/flutter/lib/src/cupertino/theme.dart
@@ -53,8 +53,7 @@ class CupertinoTheme extends StatelessWidget {
     super.key,
     required this.data,
     required this.child,
-  }) : assert(child != null),
-       assert(data != null);
+  });
 
   /// The [CupertinoThemeData] styling for this theme.
   final CupertinoThemeData data;
@@ -137,7 +136,7 @@ class _InheritedCupertinoTheme extends InheritedWidget {
   const _InheritedCupertinoTheme({
     required this.theme,
     required super.child,
-  }) : assert(theme != null);
+  });
 
   final CupertinoTheme theme;
 
@@ -528,7 +527,6 @@ class _CupertinoTextThemeDefaults {
   }
 
   CupertinoTextThemeData createDefaults({ required Color primaryColor }) {
-    assert(primaryColor != null);
     return _DefaultCupertinoTextThemeData(
       primaryColor: primaryColor,
       labelColor: labelColor,
@@ -545,9 +543,7 @@ class _DefaultCupertinoTextThemeData extends CupertinoTextThemeData {
     required this.labelColor,
     required this.inactiveGray,
     required super.primaryColor,
-  }) : assert(labelColor != null),
-       assert(inactiveGray != null),
-       assert(primaryColor != null);
+  });
 
   final Color labelColor;
   final Color inactiveGray;
diff --git a/packages/flutter/lib/src/cupertino/thumb_painter.dart b/packages/flutter/lib/src/cupertino/thumb_painter.dart
index 3c7d696d067..319c6a00e96 100644
--- a/packages/flutter/lib/src/cupertino/thumb_painter.dart
+++ b/packages/flutter/lib/src/cupertino/thumb_painter.dart
@@ -47,7 +47,7 @@ class CupertinoThumbPainter {
   const CupertinoThumbPainter({
     this.color = CupertinoColors.white,
     this.shadows = _kSliderBoxShadows,
-  }) : assert(shadows != null);
+  });
 
   /// Creates an object that paints an iOS-style switch thumb.
   const CupertinoThumbPainter.switchThumb({