Bug Weird NullReferenceException because of some Tools MonoScript

Usually i don't ask the community for help, because i can often fix my erros by myself. But this time i can't figure it out... (this error just came outta nowhere at some point)

So i get this error every time the editor refreshes:


when i click on the error it shows my this "Tools" object:


which is apparently some monoscript thing (I never saw this object and can't find it anywhere. In other projects of mine are also no "Tools" objects whatsoever).

The error doesn't "damage" my game, but it's very annoying. It appears every time and even doubles itself somehow.

Would be very nice if someone could help me