Dart Sealed Class Compile Time Error: "The type 'PossibleErrors' is not exhaustively matched by the switch cases."

Question

I am experimenting on dart`s new feature sealed classes and using it on a switch statement. I get the compile time error: The type 'PossibleErrors' is not exhaustively matched by the switch cases. Try adding a default case or cases that match PossibleErrors.

I have defined a sealed class as follows:

sealed class PossibleErrors implements Exception {
  void error(String e);
}

Afterwards I have declared 3 subclasses in the same file as follows:

class IntParseError extends PossibleErrors {
  @override
  void error(e) {
    print(e);
  }
}

class StringParseError extends PossibleErrors {
  @override
  void error(e) {
    print(e);
  }
}

class ListParseError extends PossibleErrors {
  @override
  void error(e) {
    print(e);
  }
}

Finally I have a switch statement to handle all the possible errors that can be thrown:

  try {

    throw IntParseError();

  } on PossibleErrors catch (t, e) {
    switch (t) {
      case IntParseError _:
        t.error("Int Parse Error");
      case StringParseError _:
        t.error("String Parse Error");
      case ListParseError _:
        t.error("List Parse Error");
    }
  }

The above switch statement does not compile yet all cases have been handled. Adding a default clause solves the problem but that nullifies the need to use the sealed class.[To make sure all sealed class SubClasses have been handled].

I am using the latest snapshot on the master channel. Heres my flutter --version output:

user@users-MacBook-Pro color-generator % flutter --version Flutter 3.9.0-7.0.pre.8 • channel master • https://github.com/flutter/flutter.git Framework • revision ac37dd2611 (21 hours ago) • 2023-03-14 08:14:19 -0400 Engine • revision 59e0ced91d Tools • Dart 3.0.0 (build 3.0.0-322.0.dev) • DevTools 2.22.2