Describe the bug
crash caused by async chunk loading & unloading + protosky + the aether

To Reproduce
Steps to reproduce the behavior:

1. install aether
2. install a specific version of protosky which is also in development (i will send this crash report to them as well)
3. install C2ME
4. generate chunks in the aether (i set my render distance high while doing this normally 256)
5. crash randomly while generating chunks

Expected behavior
no crash

Screenshots
N/A

Runtime info (please complete the following information):

• OS: Windows 10
• Minecraft version: 1.20.1 Fabric
• Mod version: c2me-fabric-mc1.20.1-0.2.0+alpha.11.16
• Mod branch: Default

Crash reports / logs
https://pastebin.com/qJuLLSZE

Other mods
https://www.curseforge.com/minecraft/mc-mods/aether
https://github.com/mattymatty97/ProtoSky

Checklist

• I am using the official version of the mod.
• I tried the latest development version but the issue persists.
• I searched for similar open issues and could not find an existing bug report on this.

Additional context

i narrowed this crash down to async chunk loading & unloading if i disable async chunk loading & unloading the crash will no longer happen
this is a very niche crash and, as i am using an in development build of protosky i wouldn't suggest prioritizing this crash as it is, relatively unimportant at the moment

here is a curse forge modpack with all the require mods to replicate the issue.
https://drive.google.com/file/d/18J83ecfTHVB-1_zTiXKv5t58N0q8SEfG/view?usp=sharing

Unlikely to be our problem.

https://github.com/mattymatty97/ProtoSky/blob/c29b325111cf2b9fdea52d3807833ccb195d6c0d/src/main/java/protosky/mixins/worldgen/features/ChunkMixin.java#L56

They basically shot themselves on the foot with ImmutableSet#copyOf