Engine error on Garrys mod! attempt to index a nil value

[Kenshin94]

This is what i get Lua Panic! Something went horribly wrong! " attempt to index a nil value" and i just brought the game from steam. I brought it to 2 of my friends and it works great.
Dont know what to do now. tryed most things that ppls wrote on other forums.

Is there any fix for this?