GoogleMapController getZoomLevel has CastError exception

[readyiman]

Using Google Map for Flutter with null safety

Completer<GoogleMapController> _completer = Completer();

Future<double> zoomLevel() async {
    GoogleMapController controller = await _completer.future;
    return await controller.getZoomLevel();
  }

Exception happens at controller.getZoomLevel()

Exception has occurred.
_CastError (type 'Future<double?>' is not a subtype of type 'Future<double>' in type cast)

[readyiman]

Sorry wrong package