How to show success message and catch error during flutter firestore data update

I have this function

Future updateMember(Member member) async {
  final User? user = Auth().currentUser;
  final docMember =
      FirebaseFirestore.instance.collection('users').doc(user?.uid);
  member.id = docMember.id;

  final json = member.toJson();
  final response = await docMember
      .update(json)
      .then((value) => {print("done")})
      .catchError((e) => (e));

  return response;
}

Then I want to catch the error here and success message here

  final response = updateMember(member);
              if (response.then((value) => 'done') == true) {
                ScaffoldMessenger.of(context).showSnackBar(
                  const SnackBar(
                    content: Text('success'),
                    backgroundColor: Colors.green,
                  ),
                );
              } else {
                ScaffoldMessenger.of(context).showSnackBar(
                  const SnackBar(
                    content: Text(catchError(onError)),
                    backgroundColor: Colors.red,
                  ),
                );
              }

Please I need help on how I can implement this

This solves the problem

updateMember(member)
              .whenComplete(
                  () => ScaffoldMessenger.of(context).showSnackBar(
                        const SnackBar(
                          content: Text('succes'),
                          backgroundColor: Colors.green,
                        ),
                      ))
              .onError((error, stackTrace) =>
                  ScaffoldMessenger.of(context).showSnackBar(
                     SnackBar(
                      content: Text(error.toString()),
                      backgroundColor: Colors.red,
                    ),
                  ));
        });