anchor.diff:  
     void add(data) {
       _ensureController();
  +    _reportError = false;
       _controller.add(data);
     }
   }
  
positive.code:     _completer = new Completer();
      _subscription = stream.listen(
          (data) {
            _controller.add(data);
          },
          onDone: () {
  
negative.code:                 _closeCompleter.complete(webSocket);
                },
                onError: (error) {
                  if (_reportError) {
                    if (!_done(error)) {
                      _closeCompleter.completeError(error);
                    }
                  } else {
                    _done();
                    _closeCompleter.complete(webSocket);
                  }
                });
    }
  