Would it make more sense to catch this error inside `get_case_by_identifier`? Actually, looking deeper, since the `AttributeError` is coming out of `CommCareCase.get(identifier)` inside `get_case_by_identifier`, it might make sense to either (1) coerce it to a string before calling `CommCareCase.get` or (2) do not call `CommCareCase.get` if we know that non-string values should never be passed into that function.