Bruno Leroux 1dc91d901e [Linux] Fix channel buffers control commands error handling (flutter/engine#45056)
## Description

This PR fixes a mistake I made on https://github.com/flutter/engine/pull/44636 where the error handling code wrongly relied on `fl_method_channel_invoke_method_finish` instead of  `fl_binary_messenger_send_on_channel_finish`.
The error handling code was not called when running the tests added in https://github.com/flutter/engine/pull/44636 so this mistake did not pop up.

@robert-ancell I added a test that simulates an error response and I had to rely on `g_idle_add` to make it works. Is this approach ok?

## Related Issue

Linux implementation for https://github.com/flutter/flutter/issues/132386

## Tests

Adds one test.
2023-09-01 07:40:25 +00:00
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