Shader compilation fails if custom material shaders require any shader uniform properties

CustomMaterial shader fails to compile if there are any uniforms used in shaders. The conversion of CustomMaterial's properties to uniforms fails, leading in errors about undefined variables in shaders.

This worked until recently. Currently it seems that all uniforms detect as QVariant type instead of their actual type in QQuick3DCustomMaterial::updateSpatialNode. 

The material works in preview.