isn't defined error in app_state.dart

[DavyDevelops]

The name 'Placemark' isn't a type so it can't be used as a type argument.at [136:10]

The name 'Placemark' isn't a type so it can't be used as a type argument.at [170:18]
The method 'placemarkFromCoordinates' isn't defined for the type 'Geolocator'.at [171:18]

The method 'placemarkFromCoordinates' isn't defined for the type 'Geolocator'.at [137:10]
The static method 'getCurrentPosition' can't be accessed through an instance.at [135:35]

The static method 'getPositionStream' can't be accessed through an instance.at [124:18]