Fix Cycles crash when trying to load image that does not exist
Fix Cycles crash when trying to load image that does not exist

It was crashing due to array out of bounds access. This is not a great fix,
but brings back behavior the same as before now. Perhaps images that failed
to load should be stored separately somewhere.

tangent-opensource/coreBlackbird,tangent-opensource/coreBlackbird,tangent-opensource/coreBlackbird