orCancel property

Future<void> orCancel

A future that resolves when this future resolves or throws when the ticker is canceled.

If this property is never accessed, then canceling the ticker does not throw any exceptions. Once this property is accessed, though, if the corresponding ticker is canceled, then the Future returned by this getter will complete with an error, and if that error is not caught, there will be an uncaught exception in the current zone.

Implementation 

Future<void> get orCancel {
  if (_secondaryCompleter == null) {
    _secondaryCompleter = Completer<void>();
    if (_completed != null) {
      if (_completed) {
        _secondaryCompleter.complete();
      } else {
        _secondaryCompleter.completeError(const TickerCanceled());
      }
    }
  }
  return _secondaryCompleter.future;
}