Hello,  I have been trying to use the .RayHelper constructor, but I keep getting an error saying that the RayHelper is not a constructor. I suspect that I am missing files. The ones that I have in my index.html are:  - babylon.custom.js - babylon.objFileLoader.js - babylon.objFileLoader.min.js - hand.minified-1.2.js - Oimo.js How can I fix this error?