[Crash] NullPointerException in RapierVoxelColliderBakery when processing Pixelmon MultiBlocks

[MACTEP-ABATAP]

Context

Description

A server crash occurs when Sable's physics pipeline attempts to build physics data for a MultiBlock from the Pixelmon mod.

When a Pixelmon multiblock updates or is placed, Sable triggers RapierVoxelColliderBakery.buildPhysicsDataForBlock which eventually calls getCollisionShape. Pixelmon's implementation of getShape for multiblocks attempts to query the BlockGetter for an adjacent blockstate, which returns null. This results in a NullPointerException when Pixelmon tries to invoke .getBlock() on that null state.

While the lack of null-safety is technically on Pixelmon's side, Sable is the one triggering the shape query (possibly during a state or context where Pixelmon doesn't expect it). Adding a safety check or a try-catch for third-party block shape queries during collider generation might prevent the server from crashing entirely.

Environment

• Minecraft: 1.21.1
• Modloader: NeoForge
• Sable Version: 2.0.3 (specifically sable_rapier@1.21.1-2.0.3)
• Pixelmon Version: 9.3.16

Steps to Reproduce

1. Install Sable (2.0.3) and Pixelmon (9.3.16) on a NeoForge 1.21.1 server.
2. Trigger a block state update involving a Pixelmon MultiBlock (e.g., placing or destroying a PC, Healer, or similar multiblock structure).
3. The server instantly crashes as Sable attempts to handle the block change.

Crash Report

Click to expand relevant Stacktrace

java.lang.NullPointerException: Cannot invoke "net.minecraft.world.level.block.state.BlockState.getBlock()" because the return value of "net.minecraft.world.level.BlockGetter.getBlockState(net.minecraft.core.BlockPos)" is null
	at TRANSFORMER/pixelmon@9.3.16/com.pixelmonmod.pixelmon.blocks.MultiBlock.getMultiBlockBoundingBox(MultiBlock.java:116)
	at TRANSFORMER/pixelmon@9.3.16/com.pixelmonmod.pixelmon.blocks.MultiBlock.getShape(MultiBlock.java:95)
	at TRANSFORMER/minecraft@1.21.1/net.minecraft.world.level.block.state.BlockBehaviour$BlockStateBase.getShape(BlockBehaviour.java:650)
	at TRANSFORMER/minecraft@1.21.1/net.minecraft.world.level.block.state.BlockBehaviour$BlockStateBase.getShape(BlockBehaviour.java:646)
	at TRANSFORMER/minecraft@1.21.1/net.minecraft.world.level.block.state.BlockBehaviour.getCollisionShape(BlockBehaviour.java:322)
	at TRANSFORMER/minecraft@1.21.1/net.minecraft.world.level.block.state.BlockBehaviour$BlockStateBase.getCollisionShape(BlockBehaviour.java:658)
	at TRANSFORMER/sable_rapier@1.21.1-2.0.3/dev.ryanhcode.sable.physics.impl.rapier.collider.RapierVoxelColliderBakery.buildPhysicsDataForBlock(RapierVoxelColliderBakery.java:72)
	at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1708)
	at TRANSFORMER/minecraft@1.21.1/net.minecraft.Util$8.apply(Util.java:795)
	at TRANSFORMER/sable_rapier@1.21.1-2.0.3/dev.ryanhcode.sable.physics.impl.rapier.collider.RapierVoxelColliderBakery.getPhysicsDataForBlock(RapierVoxelColliderBakery.java:98)
	at TRANSFORMER/sable_rapier@1.21.1-2.0.3/dev.ryanhcode.sable.physics.impl.rapier.RapierPhysicsPipeline.handleBlockChange(RapierPhysicsPipeline.java:395)
	at TRANSFORMER/sable@2.0.3/dev.ryanhcode.sable.sublevel.system.SubLevelPhysicsSystem.handleBlockChange(SubLevelPhysicsSystem.java:472)

### Crash Report

https://mclo.gs/Fc4rCN1