[analyzer] Soundness issue with generator element type

[eernstg]

This is the analyzer specific issue for #53052, which has the details.

[eernstg]

Just checking, this is still an issue:

import 'dart:async';

FutureOr<Iterable<int>> f() sync* {
  yield 'Hello!';
}

void main() => f();

At yield 'Hello!';, the analyzer (in DartPad based on Dart SDK 3.5.4, and on Dart SDK 3.7.0-71.0.dev) does not report any errors, even though the yielded value has type String, and the generator element type of the function should have been computed as int, but String is not assignable to int.

[eernstg]

Just checking again, this is still an issue.