Whats thie code mean?

[Someones name and SteamID here] Lua Error:

[ERROR] lua/autorun/server/admin_functions.lua:2141: Tried to use a NULL entity!

  1. GetPos - [C]:-1
  2. fn - lua/autorun/server/admin_functions.lua:2141
  3. unknown - addons/ulib/lua/ulib/shared/hook.lua:183

This appears sometimes 5 times in a row, is this person trying to use a hack?

Uhh, could you post the code that line is referring to? NULL means nil, therefore non-existent

I cant find a admin_functions.lua (or similar) file in lua/autorun/server

look into your addons folder. the subfolders also contains (mostly) an lua folder.

Ehm, admin_functions is a lua file that belongs with gmod.