Prevents landing soft-locks by cleaning null prefabs/items from LethalLib registrations before StartOfRound.Start, and names the broken mod in the log.
Rewrote the guard as a MonoMod hook installed after LethalLib's, so it actually
runs before LethalLib's fragile loop (a Harmony prefix runs at the wrong layer
and never fired).
Added CULPRIT logging: names the mod that registered a null/broken item or
enemy, using LethalLib's registration metadata.
Also sanitizes StartOfRound.allItemsList for the host-side savedata fix path.
