The Lua error reports that you may have been using a deprecated call for loading a WoW interface/AddOn.

Here is what the error text reads:

1x Vaulty/vaulty.lua:1: attempt to index global 'C_Addons' (a nil value)
[string "@Vaulty/vaulty.lua"]:1: in main chunk

Locals:
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = nil
(*temporary) = "attempt to index global 'C_Addons' (a nil value)"