To initialize the Amplify Auth and Storage categories, call `Amplify.addPlugin()` for each plugin or pass all the plugins in `Amplify.addPlugins()`. To complete initialization, call `Amplify.configure()`.

Your code should look like this:

```dart
import 'package:amplify_auth_cognito/amplify_auth_cognito.dart';
import 'package:amplify_flutter/amplify_flutter.dart';
import 'package:amplify_storage_s3/amplify_storage_s3.dart';
import 'package:flutter/material.dart';

import 'amplifyconfiguration.dart';

Future<void> _configureAmplify() async {
  try {
    final auth = AmplifyAuthCognito();
    final storage = AmplifyStorageS3();
    await Amplify.addPlugins([auth, storage]);

    // call Amplify.configure to use the initialized categories in your app
    await Amplify.configure(amplifyconfig);
  } on Exception catch (e) {
    safePrint('An error occurred configuring Amplify: $e');
  }
}

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

class MyApp extends StatefulWidget {
  const MyApp({Key? key}) : super(key: key);

  // ...
}
```