WowAce

Hello, recently i have been getting this error each time i have a friendly NPC follow me around and get in combat

468x Skada\modules\Enemies.lua:18: Usage: local className, classFilename, classID = UnitClass(unit)
[string "=[C]"]: in function `UnitClass'
[string "@Skada\modules\Enemies.lua"]:18: in function <Skada\modules\Enemies.lua:15>
[string "@Skada\modules\Enemies.lua"]:40: in function <Skada\modules\Enemies.lua:33>
[string "@Skada\modules\Enemies.lua"]:131: in function `func'
[string "@Skada\Skada-1.8.3.lua"]:1854: in function <Skada\Skada.lua:1747>
[string "@Skada\Skada-1.8.3.lua"]:1903: in function <Skada\Skada.lua:1902>

Locals:
(*temporary) = nil

I just noticed this for the first time today on my little Necrolord alt I'm playing through the primary campaign. Looks exactly the same. Haven't seen it on other characters.

Update: I've played through all the campaigns now and only Necrolord gets this error.