Steps to Reproduce the Crash

Launch the game, game crashes on startup.

Mod Pack URL (Optional)

https://www.curseforge.com/minecraft/modpacks/modded-super-flat-survival

Mod Pack Version (Optional)

1.20.1-7.2.1 Alpha

Extra Notes (Optional)

Note I am the modpack author, I am working on catching up on mod updates, and 1.20.1-7.2.1 is an alpha version primarily meant for this issue.

Crash Report

https://gist.github.com/KCtops100/15b2e574efc7471598cacf4122a50b49

Also having the same issue after attempting to upgrade 15.3.0.8 => 15.20.0.106 on 1.20.1.

This has been automatically marked as stale because it has not had recent activity, and will be closed if no further activity occurs. If this was overlooked, forgotten, or should remain open for any other reason, please reply here to call attention to it and remove the stale status. Thank you for your contributions.