Compatibility checker blocks joining a lobby (or seeing error messages) if you are using an older version.

[togera13]

The update message was blocking any potential error info etc.

The compatibility checker may have also crashed the game one time it seems.

Also seems to trigger if someone with a newer version joins an older version it can crash the game to start menu.

[VisualError]

Could you send me your log file if you ever crash with the mod again?
It's located in your game file directory/BepInEx
there should be a log file in there.