Describe the bug you're experiencing

The crash occurs normally either when I generate a chunk or when I teleport home and thus reload those chunks.

Reproducability

Travel into an ungenerated chunk or leave one that was recently generated.

Mod up to date

• Before submitting this issue I updated to the newest version and reproduced it

Minecraft version

1.21.1

Modloader version

Forge

Logs

https://gist.github.com/team1257Simon/629855e07ea4ca8bb625b570f77ecd51

The log you have attached is about entities when loading a chunk, meanwhile this mod is about saving chunks to disk in intervals so I dont really see how it is connected. Generating new chunks work just fine for me