Hot Restart does not complete if exceptions are hit during the restart

Describe the bug

First, check the All Exceptions and Uncaught Exceptions setting at debug panel.

Then debug the following example code. When debugger stoped at exception in function a, press continue button, the debugger will stoped at catch block in function b. Finally, click restart button, debugger will run into endless waiting.

import 'package:flutter/material.dart';

void a() {
  throw Exception('a');
}

void b() {
  try {
    a();
  } catch (e) {
    throw Exception('b');
  }
}

void c() {
  try {
    b();
  } catch (e) {
    throw Exception('c');
  }
}

void main() {
  runApp(App());
}

class App extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    c();
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Study Flutter',
      theme: ThemeData(
        primarySwatch: Colors.green,
      ),
      home: Container(),
    );
  }
}

Expected behavior

After I click the restart button, debugger should stopped at exception in function a

Versions (please complete the following information):

• VS Code version: 1.58.0-insider
• Dart extension version: 2.2.0
• Dart/Flutter SDK version: 3.23.1

[DanTup]

It turned out this doesn’t need any cooperation from the IDEs to fix in Flutter. The flag is per-isolate and and the restart creates new isolates, so it’s safe to just remove the flag on the existing isolates before the resume (same pace as breakpoints are removed) and the IDE already needs to set this flag on new isolates that are created.

I’ve opened a PR to move the fix to Flutter in https://github.com/flutter/flutter/pull/93411 since we needed it Flutter-side for the Flutter SDK DAP anyway.

[DanTup]

I’ve opened #3631 to track the Flutter DAP fix, as it’s a bit stalled on the main DAP work landing.