CSS Undefined Variable Checker

I was very happy to find this extension, and I is very helpful. The problem is, that if you need an extension like this it probably is because you use css-custom-properties extensively and probably also in a complex (chaining) way. I found one problematic variable but showed me others, that actually worked as faulty, and showed some that I cannot finde anywhere. So if the developers are interested in a more in detail feedback, pleas let me know. (Btw: all my CSS is served from the same server)