Game crashes when there's a structure preview and a mini-boss from Apotheosis spawns

[Athrizel]

I'm running the 1.21.1 neoforge version of spectrum. When I have a structure preview open and a mini-boss from apotheosis spawns, the game crashes entirely.

1. Run a mod that allows for structure previews as a build guide.
2. make sure to have Apotheosis installed and to be in a tier above Haven in terms of progress
3. Summon a structure preview and wait for a mini-boss to spawn
4. Crash

Expected behavior?
For the game to not crash?

System (please complete the following information):
most recent version (1.120.1)
windows
1.21.1

https://drive.google.com/file/d/16kbOQlFBsiZ34gGIba5C6ss_JG8gsm1P/view?usp=sharing Crash log