ShellLinesController.sink.addError should add errors to ShellLinesController.stream

[Conrad33]

Attempting to addError to the stream of a ShellLinesController will always result in an unhandled exception.

For example:

Stream<double> shellTask() async* {
  final output = ShellLinesController();
  Shell(stdout: output.sink).run(
    '''
       some script that doesn't return 0
    ''',
  ).then((_) => output.close(), onError: output.sink.addError); // Add error to the stream

  await for (final output in output.stream) { // This code should throw here, but it doesn't. Error isn't propagated to this stream.
    // Parse line by line and yield some formatted data
    yield formattedData;
  }
}

My current work around:

import 'package:async/async.dart';

Stream<double> shellTask() async* {
  final output = ShellLinesController();
  final errors = StreamController<Never>();
  Shell(stdout: output.sink).run(
    '''
       some script that doesn't return 0
    ''',
  ).then((_) {output.close(); errors.close();}, onError: errors.sink.addError); // Add error to the stream

  final outputStream = StreamGroup.merge<String>([output.stream, errors.stream]);
  await for (final output in outputStream ) { // Now this code throws here. 
    // Parse line by line and yield some formatted data
    yield formattedData;
  }
}

[Alexandre Roux]

Thanks for the report, the sample code and the workaround you use as it helps investigation a solution on my side. I have to admin that I never thought about errors in this simple controller. I added a fix in just published 0.13.3+1 that should hopefully work in your case. Let me know!

[Conrad33]

Works good 👍