[Bug Report] Server crash with MythicMobs block masks on MythicDungeons instance close

A player left a MythicDungeon as they lost all lives, the instance closed, then the server crashed.

There's a lot about block masks in the stacktraces, so I suspect it is causing the crash.

2 different crashes: https://mclo.gs/LYnhFfR https://mclo.gs/wOkk8ZA

Here is the issue report on MD: https://git.mythiccraft.io/mythiccraft/MythicDungeons/-/issues/247 I'm posting the issue here, in case this is something that needs to be handled by MythicMobs instead.

MythicDungeons build 142, Mythicmobs 5.2.5, Purpur 1.19.3.