Reporting issues with GraphQL-core 3

I came across an issue that may be due to Graphene but the problem surfaces here.

I was writing a mutation which would raise an Error or return:

{"data": {"someMutationThatReturnsNone": None}

instead of something like:

{"data": {"someMutationThatWillAlwaysBeTrueIfNoErrorRaised": {"success": True}}}

I was happy that this worked:

class SomeMutationThatReturnsNone(graphene.Mutation):
 class Arguments:
 ...
 Output = CustomNullTypeScalar
 def mutate(self, info: graphene.ResolveInfo, **kwargs: Any) -> None:
 ...
 return None

until I realised that this would also work:

class SomeMutationThatReturnsNone(graphene.Mutation):
 class Arguments:
 ...
 Output = graphene.Date(required=True)
 def mutate(self, info: graphene.ResolveInfo, **kwargs: Any) -> None:
 ...
 return None

currently, because the line of code linked above is before the check if is_leaf_type(return_type), so long as Output = someScalarOrEnumType the mutation will return {"data": {"someMutationThatReturnsNone": None}.
Which I don't think is right.

Would appreciate your thoughts.