Does not Navigate to page from Flutter Firebase Notification

Question

How to solve - Unhandled Exception: This widget has been unmounted, so the State no longer has a context (and should be considered defunct). Problem

when i tap on notification to navigate to LeadDetailsScreen i got error as below on Navigator context..

Please help me how i can solved this problem.

Below is my Code.

class SplashScreen extends StatefulWidget {
  @override
  _SplashScreenState createState() => _SplashScreenState();
}

class _SplashScreenState extends BaseViewState<SplashScreen>
    implements SplashContractView {
  var _log = FimberLog("Splash"); // ignore: unused_field
  late SplashContractPresenter<SplashContractView> presenter;
  final FirebaseMessaging _fcm = FirebaseMessaging.instance;
  String deviceToken = "";
  String deviceModel = "";
  String deviceName = "";
  String deviceOS = "";
  String osVersion = "";
  Map<String, dynamic> data = {};
  String? caseId;

  @override
  void initState() {
    super.initState();

    /// This method call when app is working in application to open from.
    FirebaseMessaging.onMessage.listen((RemoteMessage message) {
      RemoteNotification? notification = message.notification;
      print("notification1111 ${notification!.body}");

      print("message1111 2222 ${message.data['caseId']}");
    });

    /// This method call when app is working in background.
    FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message) {
      print('A new onMessageOpenedApp event was published!');
      RemoteNotification? notification = message.notification;
      print("notifications2222 $notification");
      AndroidNotification? android = message.notification?.android;
      if (message.notification != null) {
        CaseModel model = CaseModel();
        model.caseId = message.data["caseId"];
        print(message.data["caseId"]);
        print(model.caseId);
        print(message.notification!.title);
        print(message.notification!.body);
        print("message.data22 ${message.data['caseId']}");
        print("message.data22 ${message.data['_id']}");
        Navigator.of(context).push(
          MaterialPageRoute(
              builder: (context) => LeadDetailsScreen(caseData: model)),
        );
      }
    });

    /// This method call when app is killed(Terminated).
    killAppNotificationFunction();

    _fcm.getToken().then((token) {
      deviceToken = token.toString();
      print("Device Token:--- $token");
    });

    presenter = SplashPresenter();
    presenter.onAttach(this);
    presenter.init();
  }

  /// Kill(Terminated) app function.
  killAppNotificationFunction() async {
    RemoteMessage? terminatedMessage =
        await FirebaseMessaging.instance.getInitialMessage();

    if (terminatedMessage != null) {
      // this is a function I created to route to a page
      processKillAppPushNotification(message: terminatedMessage);
    }
  }

  void processKillAppPushNotification({RemoteMessage? message}) async {
    var notificationType;
    print("message data ${message!.data}");

    print("Processing Future after 46 seconds data ${message.data}");
    RemoteNotification? notification = message.notification;
    print("notification3333 ${notification!.body}");
    print("message1111 2222 ${message.data['caseId']}");
    print("notificationType $notificationType");
    AndroidNotification? android = message.notification?.android;
    if (notification != null && android != null) {
      print("notification Data");
      print("notification Type $notificationType");
      CaseModel model = CaseModel();
      model.caseId = message.data["caseId"];
      print(message.data["caseId"]);
      print(model.caseId);
      print(message.notification!.title);
      print(message.notification!.body);
      print("message.data22 ${message.data['caseId']}");
      print("message.data22 ${message.data['_id']}");
      Navigator.of(context).push(
        MaterialPageRoute(
            builder: (context) => LeadDetailsScreen(caseData: model)),
      );
    }
    Future.delayed(const Duration(
      seconds: 4,
    )).then((value) async {});
  }

  @override
  void dispose() {
    super.dispose();
    presenter.onDetach();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: Center(
          child: Image.asset("assets/images/1234.gif"),
        ),
      ),
    );
  }

  @override
  void openDashboard() {
    Navigator.of(context).popAndPushNamed(Constants.ROUTE_DASHBOARD);
  }

  @override
  void openLogin() {
    Navigator.of(context).popAndPushNamed(Constants.ROUTE_LOGIN);
  }
}