here is the bug :

Message: Interface\AddOns\LunaUnitFrames\modules\tags.lua:385: attempt to call global 'UnitMana' (a nil value)
Time: Mon Jun 3 11:13:22 2019
Count: 1906
Stack: Interface\AddOns\LunaUnitFrames\modules\tags.lua:385: attempt to call global 'UnitMana' (a nil value)
Interface\AddOns\LunaUnitFrames\modules\tags.lua:385: in function `?'
Interface\AddOns\LunaUnitFrames\modules\tags.lua:821: in function <Interface\AddOns\LunaUnitFrames\modules\tags.lua:811>

Locals: unit = "player"
(*temporary) = defined =[C]:-1
(*temporary) = nil
(*temporary) = "player"
(*temporary) = "attempt to call global 'UnitMana' (a nil value)"