Library Restore fails when Unit titles are blank

[ormsbee]

This may be a more general issue, but it is both legal and common for people to have untitled content in courses. The modulestore migrator can bring this content in from courses, and we can export it as a backup archive. Restoring that same data should also work.

[VAIBHAVPANT07]

Hey @ormsbee, can I take this one?

I think the issue is that the restore logic is probably choking when display_name is None instead of gracefully treating it as an empty string. Fix should be straightforward — add a null fallback where the title is read, and cover it with a regression test.

Let me know if that sounds right or if I'm missing something!

[kdmccormick]

@VAIBHAVPANT07 thanks for volunteering. Go for it! And let us know if you get stuck on anything.

Here's a first Open edX pull request guide: https://docs.openedx.org/en/latest/developers/quickstarts/first_openedx_pr.html. If you end up using nothing else in that guide, please make sure to read the CLA and AI Policy sections.

[kdmccormick]

I made a fix for this. Manually verifying it right now: openedx/openedx-core#610