Probably a rare case when it does happen, but if you swizzle the x component of a float when running in the simulator it will throw a fatal exception
PolySpatialRealityKit/PolySpatialImplUtils.swift:52: Fatal error: Could not load ShaderGraph ‘Shader Graphs/SwizzleBug’: invalidTypeFound
Simple workaround is to just not do that, and instead route the float directly.
I have created an incident for it, IN-60131