`get_runtime_errors` returns no errors for a broken Flutter app

[athomas]

I tried to get Gemini CLI to fix a broken app (red widgets with error messages, corresponding log output from flutter run) but the MCP server fails to provide this info to Gemini:

Gemini interaction:

 ✓  get_runtime_errors (dart MCP Server) {}                                                                                                      │
 │                                                                                                                                                 │
 │    No runtime errors found.     

The log contains errors and stacktraces:

══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
The following ProviderNotFoundException was thrown building Consumer2<QueryResults,
TabController>(dirty, dependencies: [_InheritedProviderScope<QueryResults?>]):
Error: Could not find the correct Provider<TabController> above this Consumer2<QueryResults,
TabController> Widget

Note: this is a flutter web app running in chrome from a debug session started in VSCode.

[jakemac53]

Ok, I have confirmed I can repro this on web, but not other platforms I have tried (MacOS, simulator).

[jakemac53]

Ok, I have tracked this down to an issue where on the web platform, errors are logged using I believe print, or possibly console.log, compared to stderr on the other platforms.

I believe the correct fix is going to be in the flutter framework, the web platform should use console.error to log errors.

Ultimately, we get these events from the VM Service stderr stream (as well as the Flutter.Error service extension stream). I am seeing all errors on the stdout stream on web though, since dwds treats console.log as equivalent to stdout.