Create OBB Collision Crash Fix

When moving contraptions collide in certain degenerate or exact-overlap cases, Create’s collision manifold fails to record a separation axis, leaving it null. The game then tries to read .x on that null Vec3 and the server crashes:

java.lang.NullPointerException: Cannot read field “x” because “mf.axis” is null
at …ContinuousOBBCollider.collideMany(ContinuousOBBCollider.java:153)
This mod uses a Mixin to intercept the two null-prone field reads (axis and normalAxis) and substitutes Vec3.ZERO when they’re null. A zero vector makes that frame’s collision contribution 0 — harmless — instead of crashing the server tick thread.

Details:

Lightweight — single mixin, no runtime overhead beyond a null check
Doesn’t modify Create’s logic, just prevents the null dereference
Works server-side (install on server only is fine, but safe on both sides)
For Create 6.0.10 on NeoForge / Minecraft 1.21.1