I keep getting this error every time I damage an NPC, it also happens when I get hurt too (I have TFA VOX callouts installed if this is anything to go by since I can't hear any pain sounds):

[Brutal NPC Deaths] lua/autorun/server/hurtmod_sv.lua:201: bad argument #1 to 'EmitSound' (string expected, got nil)
1. EmitSound - [C]:-1
2. v - lua/autorun/server/hurtmod_sv.lua:201
3. unknown - lua/includes/modules/hook.lua:96