Invalid use of a private type in a public API.Try making the private

Invalid use of a private type in a public API.
Try making the private type public, or making the API that uses the private type also be private.

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

  @override
  _DashboardPageState createState() => _DashboardPageState();
}

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

  @override
  DashboardPageState createState() => DashboardPageState();
}

class DashboardPageState extends State<DashboardPage> {