The inclusion of require("discord").setup({ ... }), as shown in the README causes the following error when launching nvim:

Error detected while processing /home/$USER/.config/nvim/init.lua:
Invalid plugin spec {

It then spits out a long list of variables (I can include the whole error message if needed, but it is moderately long.)
Nvim still loads afterwards without problem. It's just that the error is reported in the terminal every time before nvim loads.