Server-side ticking entity crash seemingly related to the thrasher AI
crash-2023-02-11_20.27.49-server.txt

Think I've encountered the same issue: https://pastebin.com/9VaYwhQm

Yep same. Also, logs spammed with [Server thread/WARN] [minecraft/ServerLevel]: Tried to add entity upgrade_aquatic:thrasher but it was marked as removed already allot of the time.

Same problem here. Do we know if this is isolated to 1.18.2?

It's not - I see it on 1.19.3 with Apathy Mod

Crashlog

Same issue on 1.19.2 https://pastebin.com/7tBraLWz

Steps to reproduce this issue:

1. Summon a Thrasher in an enclosed area of water
2. Summon any type of fish in the water
3. Right after the Thrasher grabs the fish in its mouth, run a command to kill the fish
   (/kill @e[type=salmon,limit=1,sort=nearest], replace salmon with the id of the fish you summoned)
4. The game should crash after a few seconds if the fish dies and finishes its death animation before the Thrasher finishes its attack animation.

There's a chance the game will not crash if the fish dies at the wrong time, so you might have to repeat these steps again to reproduce this issue.