Log: https://gist.github.com/FrozenGalaxy/bddcf1b6d92d01dd1b05e77557a19de0

At first glance, this seems to be an issue with an installed mod that provides the krypton.mixins.json:shared.network.avoidwork.ThreadedAnvilChunkStorageMixin mixin. Please report this issue to that mod's author and optionally cross-reference this issue report so we can communicate more easily. Thanks :)