Create: Contraption (VirtualWorld) Compat
A universal compatibility mod that fixes crashes when placing block entities from various mods on Create contraptions.
Disclaimer: Yes this Mod was made using AI, as this Description too. AI was used for the code, specs and tests where done by me. Security audit was done by AI.
The Problem
In **Create 6.0.8**, placing certain block entities on contraptions causes the game to crash with:
java.lang.UnsupportedOperationException: VirtualRenderWorld doesn't maintain a chunk array. at com.simibubi.create.content.contraptions.render.VirtualRenderWorld.getChunk(VirtualRenderWorld.java:69)This is FIXED in Create 6.0.9
This occurs because Create 6.0.8 introduced a change where block entities are loaded into a `VirtualRenderWorld` before their NBT data is processed. When block entities call `setChanged()` during initialization, it triggers `Level.blockEntityChanged()` which tries to mark chunks as unsaved - but `VirtualRenderWorld` is a lightweight render-only world that doesn't support chunk operations.
The Solution
This mod uses a Mixin to intercept calls to `Level.blockEntityChanged()` and cancels them when the level is a `VirtualRenderWorld`. Since `VirtualRenderWorld` is temporary and never persists, marking chunks as unsaved is unnecessary and can be safely skipped.
undefined
@Mixin(value = Level.class)public class VirtualRenderWorldMixin { @Inject(method = "blockEntityChanged", at = @At("HEAD"), cancellable = true) public void preventBlockEntityChangedInVirtualWorld(BlockPos pos, CallbackInfo ci) { if ((Object) this instanceof VirtualRenderWorld) { ci.cancel(); } }}
Compatibility
Affected Mods
This fix is **universal** and works with any mod where block entities call `setChanged()` during loading:
### Requirements
- **Minecraft**: 1.21.1
- **NeoForge**: 21.1.209+
- **Create**: 6.0.8 (the issue doesn't exist in 6.0.6 and earlier)
- **Flywheel**: 1.0.5
## Credits
- **Create Team** - For the amazing Create mod
- **NeoForge Team** - For the modding framework

