'Undefined name' error when using Supabase in Custom Action for Login with Discord

I'm trying to implement Discord login in my FlutterFlow app using Supabase as backend. To do this, I created a Custom Action and inserted the following Flutter code:

Future<void> signInWithDiscord() async {
  try {
    await Supabase.instance.client.auth.signInWithOAuth(Provider.discord);
  } catch (e) {
    print('Erro ao fazer login com Discord: $e');
  }
}

However, when trying to compile the Custom Action, I am getting the following errors:

Undefined name 'Supabase'. Try correcting the name to one that is defined, or defining the name. (Line [indicate the line in your code])
Undefined name 'Provider'. Try correcting the name to one that is defined, or defining the name. (Line [indicate the line in your code])

I have already configured the Supabase backend in my FlutterFlow project with the correct project URL and anonymous key.

I added the dependency supabase_flutter in pubspec.yaml from FlutterFlow, as per the instructions.
I have checked and confirmed that my Supabase project URL and anonymous key are correct in FlutterFlow settings.
I tried using different versions of the dependency supabase_flutter in pubspec.yaml.
I saved the changes, closed and reopened FlutterFlow.
I checked that there is only one import of the Supabase library in my Custom Action:import '/backend/supabase/supabase.dart';.
I made sure there are no typos or indentation issues in the Custom Action code.
I tried to run code generation in FlutterFlow.

Even after these attempts, the error persists. Has anyone faced a similar issue while using Supabase in Custom Actions in FlutterFlow? Is there any additional configuration or step that I might have missed?