Lua error [darkrp]

Hi, this is the error I got last night after installing a recent printer addon

[ERROR] addons/darkrpmodification/lua/entities/k_coolant_cell/cl_init.lua:5: Tried to use a NULL entity!

  1. GetClass - [C]:-1
  2. fn - addons/darkrpmodification/lua/entities/k_coolant_cell/cl_init.lua:5
    3. unknown - addons/ulib/lua/ulib/shared/hook.lua:183

This is the printer addon page: http://forum.facepunch.com/showthread.php?t=1282076

Help?

Add this line above it:


if not ( IsValid( tr.Entity ) ) then return end;

Where?

Above the line that is erroring.