These keep popping up. If I restart unity editor it goes away briefly then comes right back. It’s not preventing builds or anything.
That’s a good question. I have seen these kind of things appear in the console ever since I first started using Unity. Not always just randomly. Messages about GUI things being NULL or something in the Editor window not found and so forth. Then they randomly go away. Then come back again. I think they are often linked to some 3rd party asset but not always.
I’ve just always ignored them and had no problems.