setAppState method
Assign the class with the AppState object.
Implementation
bool setAppState(v.AppState? vw) {
  // Don't continue if an app called an app.
  final set = vw != null && (_appState == null || hotReload);
  if (set) {
    //
    _appState = vw;
    // Assign the 'app' object to the app's view
    vw.app = this;
  }
  return set;
}