POC necessário para mostrar o erro [ Null check operator used on a null value] que só aparece em RELEASE

main.dart

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'dart:async';

void main() {
  // Initialize our error logger before running the app.
  ErrorLogger.initialize();
  runApp(MyApp());
}

class ErrorLogger {
  // Using a ValueNotifier to update the UI whenever the log changes.
  static final ValueNotifier<String> logNotifier = ValueNotifier<String>('');

  static void initialize() {
    FlutterError.onError = (FlutterErrorDetails details) {
      // Also append the error to your custom log.
      ErrorLogger.logNotifier.value +=
          "\n-------------\n" + details.toString() + "\n";
    };

// Pass all uncaught asynchronous errors that aren't handled by the Flutter framework to Crashlytics.
    PlatformDispatcher.instance.onError = (error, stack) {
      // Also append the error and stack trace to your custom log.
      ErrorLogger.logNotifier.value += "\n-------------\nError: $error\nStack: $stack\n";
      return true;
    };
  }
}

class CallbackManager {
  CallbackManager._();
  static final CallbackManager instance = CallbackManager._();

  /// Registered callback that can be triggered externally.
  VoidCallback? onCallback;

  /// Method to trigger the callback if it is registered.
  void triggerCallback() {
    if (onCallback != null) {
      onCallback!();
    }
  }
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Test Callback with Navigation',
      initialRoute: '/',
      routes: {
        '/': (context) => const HomeScreen(),
        '/dummy': (context) => const DummyScreen(),
      },
    );
  }
}

class HomeScreen extends StatelessWidget {
  const HomeScreen({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Home - CallbackWidget'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          children: [
            const SizedBox(height: 20),
            // Button to trigger the callback.
            ElevatedButton(
              onPressed: () {
                CallbackManager.instance.triggerCallback();
              },
              child: const Text('Trigger Callback'),
            ),
            const SizedBox(height: 20),
            // Button to navigate to another screen.
            ElevatedButton(
              onPressed: () {
                Navigator.pushNamed(context, '/dummy');
              },
              child: const Text('Navigate to another screen'),
            ),
            const SizedBox(height: 20),
            const Text(
              'Flutter Error Log:',
              style: TextStyle(fontWeight: FontWeight.bold),
            ),
            // The "textarea" displaying errors.
            Expanded(
              child: Container(
                decoration: BoxDecoration(
                  border: Border.all(color: Colors.grey),
                ),
                width: double.infinity,
                padding: const EdgeInsets.all(8.0),
                child: ValueListenableBuilder<String>(
                  valueListenable: ErrorLogger.logNotifier,
                  builder: (context, log, child) {
                    return SingleChildScrollView(
                      child: Text(
                        log,
                        style: const TextStyle(fontSize: 12, color: Colors.red),
                      ),
                    );
                  },
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

class DummyScreen extends StatefulWidget {
  const DummyScreen({super.key});

  @override
  State<DummyScreen> createState() => _DummyScreenState();
}

class _DummyScreenState extends State<DummyScreen> {
  bool _callbackFired = false;

  @override
  void initState() {
    super.initState();
    // Register a callback that intentionally causes an error by calling setState after dispose.
    CallbackManager.instance.onCallback = () {
      Timer(const Duration(seconds: 1), () {
        // This will trigger an error if the widget has been disposed.
        setState(() {
          _callbackFired = true;
        });
      });
    };
  }

  @override
  void dispose() {
    // Clear the callback to avoid potential errors.
    // CallbackManager.instance.onCallback = null;
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Dummy Screen'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          children: [
            const Text(
              'This is a dummy screen.\nThe CallbackWidget has been disposed.',
              style: TextStyle(fontSize: 20),
              textAlign: TextAlign.center,
            ),
            const SizedBox(height: 20),
            ElevatedButton(
              onPressed: () {
                Navigator.pop(context);
              },
              child: const Text('Go Back'),
            ),
          ],
        ),
      ),
    );
  }
}