It looks like you're returning three different types in this function: `None` if we don't have a course module, the list `[prev_section, next_section]` if we can find the active chapter and settings, and the tuple `(None, None)` if we don't have any display items. I think we should be using tuples consistently, such that we're returning `(prev_section, next_section)` when we have the content we need and `(None, None)` when we don't.