I’ve discovered a nasty crash bug involving the Join menu and session searching. Not sure if this is covered in the ‘Debugging Engine’ lecture, so I thought I’d bring it up just in case.
If the joining player backs out of the search, and then re-enters the Join menu and clicks join before the list refresh completes, they will spawn into the level and almost immediately crash. Waiting until the search is complete allows the client to connect without issue.