link.dart

if (snapshot.error == null) {
  final String downloadUrl =
      await snapshot.ref.getDownloadURL();
  await Firestore.instance
      .collection("images")
      .add({"url": downloadUrl, "name": imageName});
  setState(() {
    isLoading = false;
  });
  final snackBar =
      SnackBar(content: Text('Yay! Success'));
  Scaffold.of(context).showSnackBar(snackBar);
} else {
  else {
  print(
      'Error from image repo ${snapshot.error.toString()}');
  throw ('This file is not an image');
   }
  });
});