NullPointerException in lighting on world rejoin after disassembling sub-level (only occurs with Tellus mod)

[zerosama-sorasaki]

Context

Assembling a structure with the physics assembler and then converting the sub-level back into normal blocks works fine while the world is running. However, after leaving and rejoining the world, the game crashes with a NullPointerException in the lighting system.

This only happens when the Tellus mod is present.
Without Tellus, the same steps work flawlessly (no crash on rejoin).

Reproduction steps:

1. Load a world with Sable 2.0.5 + Create Aeronautics (physics assembler) and Tellus.
2. Assemble a structure into a sub-level using the physics assembler.
3. Convert the sub-level back into normal blocks.
4. Game continues to run normally.
5. Leave the world and rejoin → immediate crash.

Environment:

Minecraft 1.21.1
NeoForge 21.1.248
Sable 2.0.5
Tellus 0.8.2
Create Aeronautics

Crash Report

https://mclo.gs/OSpGzoq