IMO if the security of a system depends on the lock screen not crashing then the system is not very secure. Security protocols should never fail open like that; a lock screen should never simply be a layer on top of the authenticated desktop. Windows and macOS get this right. I believe Wayland display managers are also able to get this right (but I haven't checked).

Yes, Wayland should fix this. Granted, then you have a locked screen that the user may or may not be able to unlock, which is awkward if better.