void main() => runApp( DevicePreview( enabled: !kReleaseMode, builder: (context) => MyApp(), // Wrap your app ), ); class MyApp extends StatelessWidget { final botToastBuilder = BotToastInit(); @override Widget build(BuildContext context) { return GetMaterialApp.router( useInheritedMediaQuery: true, locale: DevicePreview.locale(context), builder: (context, child) { child = DevicePreview.appBuilder(context, child); child = botToastBuilder(context, child); return child; }, theme: ThemeData.light(), darkTheme: ThemeData.dark(), home: const HomePage(), ); } } Reference: https://pub.dev/packages/bot_toast https://stackoverflow.