listenAppleIDSignInOnFailure function Null safety

StreamSubscription<Event> listenAppleIDSignInOnFailure(
  1. dynamic callback(
    1. Event
    )
)

Implementation

StreamSubscription<Event> listenAppleIDSignInOnFailure(
    Function(Event) callback) {
  _subAppleIDSignInOnFailure?.cancel();
  return _subAppleIDSignInOnFailure ??=
      document.on['AppleIDSignInOnFailure'].listen(callback);
}