Flutter: "Null check operator used on a null value" without Null check operator

I am building a project in flutter and encountered this error that is mentioning the Null check operator, but I am not using a null check operator.

I have tried all the suggestions I could find in other posts. flutter clear etc.

The only solutions I can find reference the null check operator which is not present in my code.

Could someone please help?

This is the console output when running flutter run. The $appRoute printing is working perfectly so it definitely isn’t null.

available at: http://127.0.0.1:65311/771_ENJaKJI=/
I/flutter ( 9180): AppRoutes: {/: Closure: (dynamic) => HomeScreen, /login: Closure: (dynamic) => LoginScreen, /topics: Closure: (dynamic) => TopicsScreen, /profile: Closure: (dynamic) => ProfileScreen, /about: Closure: (dynamic) => AboutScreen}

══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY
╞═══════════════════════════════════════════════════════════
The following _CastError was thrown building Builder:
Null check operator used on a null value

The relevant error-causing widget was:
  MaterialApp
  MaterialApp:file:///Users/lbeckert/dev/chatapp/lib/main.dart:58
  :18

When the exception was thrown, this was the stack:
#0      _WidgetsAppState._onGenerateRoute.<anonymous closure>
(package:flutter/src/widgets/app.dart:1422:48)
#1      MaterialPageRoute.buildContent
(package:flutter/src/material/page.dart:53:55)
#2      MaterialRouteTransitionMixin.buildPage
(package:flutter/src/material/page.dart:111:27)
...

═════════════════════════════════════════════════════════════════
═══════════════════════════════════
The Flutter DevTools debugger and profiler on sdk gphone arm64 is
available at:
http://127.0.0.1:9101?uri=http://127.0.0.1:65311/771_ENJaKJI=/

Here is my main.dart file:

import 'package:chatapp/routes.dart';
import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

import 'package:chatapp/about/about.dart';
import 'package:chatapp/profile/profile.dart';
import 'package:chatapp/login/login.dart';
import 'package:chatapp/topics/topics.dart';
import 'package:chatapp/home/home.dart';

// Import the firebase_core plugin
import 'package:firebase_core/firebase_core.dart';
import 'services/firebase_options.dart';

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  runApp(const App());
}

/// We are using a StatefulWidget such that we only create the [Future] once,
/// no matter how many times our widget rebuild.
/// If we used a [StatelessWidget], in the event where [App] is rebuilt, that
/// would re-initialize FlutterFire and make our application re-enter loading state,
/// which is undesired.
class App extends StatefulWidget {
  const App({super.key});

  @override
  State<App> createState() => _AppState();
}

class _AppState extends State<App> {
  Future<FirebaseApp> _initialization = Firebase.initializeApp(
    options: DefaultFirebaseOptions.currentPlatform,
  );

  @override
  Widget build(BuildContext context) {
    return FutureBuilder(
      future: _initialization,
      builder: (context, snapshot) {
        // Check for errors
        if (snapshot.hasError) {
          return const MaterialApp(
            home: Scaffold(
              body: Center(
                child: Text('error'),
              ),
            ),
          );
        }

        // Once complete, show your application
        if (snapshot.connectionState == ConnectionState.done) {
          print('AppRoutes: $appRoutes');
          return MaterialApp(
            routes: appRoutes,
          );
        }

        // Otherwise, show something whilst waiting for initialization to complete
        return const MaterialApp(
          home: Scaffold(
            body: Center(
              child: Text('loading'),
            ),
          ),
        );
      },
    );
  }
}

My routes.dart file:

import 'package:chatapp/profile/profile.dart';
import 'package:chatapp/login/login.dart';
import 'package:chatapp/topics/topics.dart';
import 'package:chatapp/home/home.dart';

var appRoutes = {
  '/': (context) => const HomeScreen(),
  '/login': (context) => const LoginScreen(),
  '/topics': (context) => const TopicsScreen(),
  '/profile': (context) => const ProfileScreen(),
  '/about': (context) => const AboutScreen(),
};

My home.dart file:

import 'package:flutter/src/widgets/placeholder.dart';
import 'package:flutter/material.dart';

class HomeScreen extends StatelessWidget {
  const HomeScreen({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: ElevatedButton(
          child: Text('about'),
          onPressed: () => Navigator.pushNamed(context, '/about'),
        ),
      ),
    );
  }
}

and my about.dart file:

import 'package:flutter/src/widgets/placeholder.dart';
import 'package:flutter/material.dart';

class AboutScreen extends StatelessWidget {
  const AboutScreen({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
    );
  }
}