Crash: "Sub-level assembly attempted inside plot of already removed sub-level" during Tree Physics + Aeronautics interaction #1344

Context

Summary
Server crashed with a RuntimeException from Sable's SubLevelAssemblyHelper.assembleBlocks
while a tree was being cut/falling near a Create Aeronautics airship. The exception message
was: "Sub-level assembly attempted inside plot of already removed sub-level".

What we were doing
We were cutting down trees to harvest wood for airship fuel while parked at/near our
airship. The crash happened right after another tree fell nearby. On rejoining, the
airship was completely gone.

Relevant stack trace
java.lang.RuntimeException: Sub-level assembly attempted inside plot of already removed sub-level
at dev.ryanhcode.sable.api.SubLevelAssemblyHelper.assembleBlocks(SubLevelAssemblyHelper.java:85)
[mixins: aeronautics.mixins.json:balloon.SubLevelAssemblyHelperMixin from mod aeronautics,
treephysics.mixins.json:tree_splitting.SubLevelAssemblyHelperMixin from mod treephysics]
at dev.ryanhcode.sable.sublevel.plot.heat.SubLevelHeatMapManager.split(SubLevelHeatMapManager.java:242)
at dev.ryanhcode.sable.sublevel.plot.heat.SubLevelHeatMapManager.step(SubLevelHeatMapManager.java:118)
at dev.ryanhcode.sable.sublevel.plot.heat.SubLevelHeatMapManager.tick(SubLevelHeatMapManager.java:85)
at dev.ryanhcode.sable.sublevel.ServerSubLevel.tick(ServerSubLevel.java:235)
at dev.ryanhcode.sable.api.sublevel.SubLevelContainer.tick(SubLevelContainer.java:144)
at dev.ryanhcode.sable.api.sublevel.ServerSubLevelContainer.tick(ServerSubLevelContainer.java:90)

Impact
The airship and its full contents were completely lost on restart — no partial
recovery, no automatic backup triggered.

Versions

• Sable: 2.0.3
• Sable Companion: 1.6.0
• Create Aeronautics: 1.3.0
• Tree Physics: 2.2
• Minecraft/NeoForge: 1.21.1

Full crash report attached.

Crash Report

https://mclo.gs/Sk2bNaM