Causes the game to crash on world load when used in combination with Polytone.

latest.log

I'm not entirely sure that Polytones is directly incompatible here, the error involves tags being unbound, which implies that the world is rendering before tags have been synced. I can certainly add exception handling to this method to prevent a hard world crash, but it is odd.

Have you directly tested Polytones in: crash -> remove Polytones: no crash?

Yes, both mods work without the other. So, just Polytone works and just Particle Core works, but together they do not. This also wasn't happening before I updated to 1.21.4 from 1.21.