But, it’d provide the name of the addon with the file, then we can go from there.
Before we do that though, try one more thing. Search *.vmt, and *.vtf files in Garrys Mod using Notepad++ for some Lua, try include or AddCSLuaFile, and that function call. If it was the cough, there may be modified vtf/vmt files with Lua within.
You can also search gma files the same way; any embedded Lua file is plain-text, I’d suggest that first, the texture files second, then the output all third.