From d75fb40585339549ad6b332573525662dfcd5f12 Mon Sep 17 00:00:00 2001
From: Collin Jackson <jackson@google.com>
Date: Fri, 21 Aug 2015 11:18:10 -0700
Subject: [PATCH] =?UTF-8?q?Don=E2=80=99t=20flash=20a=20message=20while=20f?=
 =?UTF-8?q?itness=20data=20is=20loading?=
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---
 examples/fitness/lib/feed.dart              |  2 ++
 examples/fitness/lib/main.dart              |  2 +-
 packages/flutter/lib/widgets/framework.dart | 14 +++++++++-----
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/examples/fitness/lib/feed.dart b/examples/fitness/lib/feed.dart
index d9ae7361836..6f149fd1dcd 100644
--- a/examples/fitness/lib/feed.dart
+++ b/examples/fitness/lib/feed.dart
@@ -214,6 +214,8 @@ class FeedFragment extends StatefulComponent {
 
   Widget buildBody() {
     TextStyle style = Theme.of(this).text.title;
+    if (userData == null)
+      return new Material(type: MaterialType.canvas);
     if (userData.items.length == 0)
       return new Material(
         type: MaterialType.canvas,
diff --git a/examples/fitness/lib/main.dart b/examples/fitness/lib/main.dart
index 0755d56559e..339c7a88e27 100644
--- a/examples/fitness/lib/main.dart
+++ b/examples/fitness/lib/main.dart
@@ -86,7 +86,7 @@ class UserDataImpl extends UserData {
 
 class FitnessApp extends App {
   NavigationState _navigationState;
-  UserDataImpl _userData = new UserDataImpl();
+  UserDataImpl _userData;
 
   void didMount() {
     super.didMount();
diff --git a/packages/flutter/lib/widgets/framework.dart b/packages/flutter/lib/widgets/framework.dart
index e9720dfe87e..60df57c2b11 100644
--- a/packages/flutter/lib/widgets/framework.dart
+++ b/packages/flutter/lib/widgets/framework.dart
@@ -425,10 +425,14 @@ abstract class TagNode extends Widget {
   void _sync(Widget old, dynamic slot) {
     Widget oldChild = old == null ? null : (old as TagNode).child;
     child = syncChild(child, oldChild, slot);
-    assert(child.parent == this);
-    assert(child.renderObject != null);
-    _renderObject = child.renderObject;
-    assert(_renderObject == renderObject); // in case a subclass reintroduces it
+    if (child != null) {
+      assert(child.parent == this);
+      assert(child.renderObject != null);
+      _renderObject = child.renderObject;
+      assert(_renderObject == renderObject); // in case a subclass reintroduces it
+    } else {
+      _renderObject = null;
+    }
   }
 
   void updateSlot(dynamic newSlot) {
@@ -1146,7 +1150,7 @@ abstract class MultiChildRenderObjectWrapper extends RenderObjectWrapper {
           syncChild(null, oldChild, null);
         }
         oldChildrenBottom -= 1;
-      }      
+      }
     }
 
     // middle of the lists - new list