Stream.pipe should return a Future<void>

[srawlins]

The implementation for Stream.pipe is:

Future pipe(StreamConsumer<T> streamConsumer) {
  return streamConsumer.addStream(this).then((_) => streamConsumer.close());
}

Shouldn't this method return Future<void> rather than Future<dynamic>? My motivation is for #35825, where I'm catching code like:

myStream
  .pipe(something)
  .catchError((e) => print(e));

So Future<dynamic>.catchError's onError handler should return FutureOr<dynamic>, and returning void from the handler would be an error.

[lrhn]

Yes, it should.
I guess it's technically a breaking change if anyone uses the result, but nobody should be using it.

[SteveAlexander]

The docs for pipe say "The returned future completes with the same result as the future returned by [StreamConsumer.close]. If the call to [StreamConsumer.addStream] fails in some way, this method fails in the same way."

This makes sense, because StreamConsumer.close says the return value is used for error reporting:
"Returns a future which is completed when the consumer has shut down. If cleaning up can fail, the error may be reported in the returned future, otherwise it completes with null."

I guess StreamConsumer<S> could be changed to StreamConsumer<S, E>, with a new generic type for the return type of close. But I don't think I've seen this feature of close used before.

[Baksman]

In case anyone is having such issue