问Flutter Firebase存储实例似乎未初始化

EN

Future<void> main() async{

    // setup camera
    WidgetsFlutterBinding.ensureInitialized();
    final cameras = await availableCameras();

    // look here!!
    print('firestore: ${Firestore.instance.app}');
    print('storage:   ${FirebaseStorage.instance.app}');

    runApp(MyApp(cameras: cameras));
}

Restarted application in 1,097ms.
flutter: firestore: FirebaseApp(__FIRAPP_DEFAULT)
flutter: storage:   null

  # Firebase
  firebase_core: ^0.4.0+9
  firebase_analytics: ^5.0.2
  firebase_auth: ^0.14.0+5
  cloud_firestore: ^0.12.9+5
  firebase_storage: ^3.0.8

    // saves a locally stored image at local_uri as name. After the storage task
    // is complete, the DocumentReference ref is updated with the new url
    Future<void> _save_storage(String name, String local_uri, DocumentReference ref) async {
        StorageReference storage_reference;

        storage_reference = FirebaseStorage.instance.ref().child('images/$name');

        final StorageUploadTask upload_task = storage_reference.putFile(io.File(local_uri));
        final StorageTaskSnapshot download_url = (await upload_task.onComplete);
        final String url = (await download_url.ref.getDownloadURL());

        // now, update the file in the database to point to the correct storage
        // url
        Firestore.instance.runTransaction((transaction) async {
            await transaction.update(ref, {'image_url' : url});
        });
    }