Flywheel Crash Fix

Flywheel Crash Fix is a lightweight client-side Forge mod for Minecraft 1.20.1 that eliminates a NullPointerException crash triggered by Create's visual rendering system.

The Problem

When the Create mod renders its machines using the Flywheel rendering engine, the FrogportVisual and ChainConveyorVisual classes iterate over every item a Frogport or Chain Conveyor is currently handling. For each item they attempt to look up a registered visual model. If no model is registered for that item — which happens with package items from Create Mobile Packages that failed model registration — Flywheel receives a null partial model reference and throws a NullPointerException, immediately crashing the game client.

The Fix

This mod injects three Mixins into the Flywheel/Create rendering pipeline:

Mixin What it does AbstractBEVisualAccessorMixin Exposes the protected level field on AbstractBlockEntityVisual so downstream mixins can safely read it. FrogportVisualMixin Wraps the item-rendering loop in FrogportVisual with a null-check guard; skips any item whose visual model lookup returns null. ChainConveyorVisualMixin Applies the same null-check guard to ChainConveyorVisual's item-rendering loop.

The fix is purely defensive — if models are correctly registered the code path is unchanged. No gameplay behaviour, item behaviour, or server logic is affected.

Compatibility

Requirement Version Minecraft 1.20.1 Forge 47.4.16+ Create 6.0.8+ Flywheel 1.0.5

This mod is client-side only and does not need to be installed on a dedicated server.

Why Does This Happen?

Create Mobile Packages registers visual models for its package items during the Flywheel model-registration phase. Under certain mod-loading orders or when model registration is interrupted, the registration fails silently and leaves a null entry in the model registry. Flywheel does not guard against this, so the first time a Frogport or Chain Conveyor tries to render one of those items the JVM throws and the game crashes.

The permanent fix is for Create Mobile Packages to harden its own model registration. Until that upstream fix is released, this mod provides a safe workaround.