RuntimeError: Error: Circular reference in texture stack (I'm using CATS plugin)

Using the CATS plugin for Blender, I’m clicking atlas and it is coming up with this error that I’ll attach as a screenshot. This is not my model and I won’t be using it for commercial use. I’m a complete rookie at Blender and I’ve only started using it today, sorry if this Isn’t enough info to help me with my problem!