EventSink with a _Socket sink throws no instance method 'addError'

[algobardo]

import "dart:io";
import "dart:async";
void main() async {
  Process p = await Process.start("ls", []);
  p.stdin.addError(new Exception());
}

causes

Unhandled exception:
Class '_Socket' has no instance method 'addError'.

NoSuchMethodError: method not found: 'addError'
Receiver: Instance of '_Socket'
Arguments: [Instance of '_Exception', null]
#0      Object._noSuchMethod (dart:core-patch/object_patch.dart:42)
#1      Object.noSuchMethod (dart:core-patch/object_patch.dart:45)
#2      _StdSink.addError (dart:io/stdio.dart:262)