Gmod 13 open beta: sky is pink and black checkered

I installed the Garry’s Mod 13 open beta yesterday and the sky is all pink and black checkered. I have HL2, HL2:Lost Coast and TF2. Is there another game or download I need to have, or is it a bug that hasn’t been fixed yet? I can be patient if it’s a bug; I know Garry and his team are very busy and I don’t want to rush them. In the meantime, I’d just like to know if anybody has an idea what could be causing this and/or what I can do to fix it. Does anybody else have this problem?

EDIT: Never mind, I’m stupid. I had to disable a mod that I downloaded from the toybox/addons thingy. If anybody else is having this problem, for me it was caused by a mod called “Atmosphere” and I apparently didn’t have the textures for it. Sorry for wasting your time.