Unable to create a Dismiss button as the `mainButton`

[thefirebanks]

Describe the bug Trying to create a Flushbar that gets dismissed when the user presses a button following the example here, but 2 issues come up:

• The FlatButton widget is deprecated (so I'm using a TextButton instead)
• I can't define a button that when pressed it dismisses the flushbar because of this error: The non-nullable local variable 'flush' must be assigned before it can be used. Try giving it an initializer expression, or ensure that it's assigned on every execution path.

To Reproduce Steps to reproduce the behavior:

This is my current code:

class NotificationService {
  final FirebaseMessaging _firebaseMessaging = FirebaseMessaging.instance;

  void initialize(BuildContext context) async {
    await _firebaseMessaging.requestPermission();
    String? initialToken = await _firebaseMessaging.getToken();

    if (initialToken != null) {
      // Send the initial token to your server for user/device association
      print("Initial Device Token: $initialToken");
    }

    _firebaseMessaging.onTokenRefresh.listen((newToken) {
      // Send the new token to your server for user/device association
      print("Refreshed Device Token: $newToken");
    });

    FirebaseMessaging.onMessage.listen(
      (RemoteMessage message) {
        // Handle the incoming message here
        print(
            'Foreground notification received: ${message.notification?.title}');

        String notificationTitle = message.notification?.title ?? '';
        String notificationMessage = message.notification?.body ?? '';

        Flushbar flush;
        flush = Flushbar<bool>(
          title: notificationTitle,
          message: notificationMessage,
          flushbarPosition: FlushbarPosition.TOP,
          flushbarStyle: FlushbarStyle.FLOATING,
          duration: Duration(seconds: 5),
          mainButton: TextButton(
            child: Text(
              "Dismiss",
              style: TextStyle(color: Colors.amber),
            ),
            onPressed: () {
              flush.dismiss(true);
            },
          ),
        );
        flush.show(context);

      },
    );

    FirebaseMessaging.onMessageOpenedApp.listen(
      (RemoteMessage message) {
        // Handle when the user taps the notification while the app is in the background
        print("User tapped the notification: ${message.notification?.title}");
      },
    );
  }

}

Which doesn't fully build because of the error, so I can't initialize the app.

Expected behavior The app should initialize and the button should be created.

Smartphone (please complete the following information):

• Device: Pixel 6a
• OS: Android

[thefirebanks]

UPDATE: Solved it by adding a late modifier to flush:

        late Flushbar flush;
        flush = Flushbar<bool>(
          title: notificationTitle,
          message: notificationMessage,
          flushbarPosition: FlushbarPosition.TOP,
          flushbarStyle: FlushbarStyle.FLOATING,
          duration: Duration(seconds: 5),
          mainButton: TextButton(
            child: Text(
              "Dismiss",
              style: TextStyle(color: Colors.amber),
            ),
            onPressed: () {
              flush.dismiss(true);
            },
          ),
        );
        flush.show(context);

But I'll keep this here in case anyone else runs into a similar issue

[rt234cw]

finally found the solution!!! Big thanks