I ran in to this problem while exploring the Ashed king fortress structure. The first five minutes were fine until i was fighting multiple different enemies.

when trying to recreate the crash on the server i came across 4 different crashes. these crashes either occur immediately or after 1-10 minutes upon spawning/encountering these enemies.

Either the client or server crashes while being near a fell mage.

crash-2024-07-15_15.07.26-client.txt
crash-2024-07-15_21.22.24-server.txt

The same type of issue happens sometimes when i spawn/encounter the fell knight.

crash-2024-07-15_22.20.42-client.txt

i got the 4th crash when testing the ashed king by spawning it in its structure using the key. this crash also occured when i tried to spawn it with a spawnegg

crash-2024-07-15_15.15.55-client.txt

being near these enemies in singleplayer seems to be fine.

Glad to hear they are all fixed, issue shall be closed. But do let me know if you come across any more of course. Thank you for testing on multiplayer!