crash-2021-11-18_17.10.32-server.txt
I was hit by this one just recently. Something about my use of "on callbacks". but I've never had it happen before this.

Forge: 36.28
Origins: 1.16.5-0.7.3.9-forge
Architectury: 1.24.35-forge.jar

on_added also triggers when an entity is loaded, not just when the power is gained, that's a limitation of the 1.16.5 version.
I'll make a bugfix pass on 1.16.5 when I have something akin to a stable release on 1.17.

The issue here is that basically you are trying to play a sound when the power is added, and at that moment the server may not be fully initialized.

oh. well. poot... wait...but..

it's not a sound. I'm applying fire resistance to the wraith so when they join if they joined outside in the daytime when they left at night time they don't immediately catch fire while they've got login lag... similarly on death and respawn for all origins, they respawn with a resistance 5 shield for a bit.

Same issue, it's applied before any synchronization could be done, so the client player exists, not the server.
Minecraft is stupid sometimes.

ah, well thats a maximum frick. so action_added bad. I'll disable that for now and just hope people don't super derp.