WowAce

10x ...ura/Libs/LibPlayerSpells-1.0-15/LibPlayerSpells-1.0.lua:440: attempt to call upvalue 'GetSpellInfo' (a nil value)
[string "@PitBull4/Modules/Aura/Libs/LibPlayerSpells-1.0-15/LibPlayerSpells-1.0.lua"]:440: in function <...ura/Libs/LibPlayerSpells-1.0/LibPlayerSpells-1.0.lua:428>
[string "@PitBull4/Modules/Aura/Libs/LibPlayerSpells-1.0-15/LibPlayerSpells-1.0.lua"]:546: in function `__RegisterSpells'
[string "@PitBull4/Modules/Aura/Libs/LibPlayerSpells-1.0-15/data/Racials.lua"]:23: in main chunk

Locals:
spellId = 331868
spellType = "spell"
errors = <table> {
}
(*temporary) = nil
(*temporary) = 331868
(*temporary) = "attempt to call upvalue 'GetSpellInfo' (a nil value)"
FilterSpellId = <function> defined @PitBull4/Modules/Aura/Libs/LibPlayerSpells-1.0/LibPlayerSpells-1.0.lua:428
tinsert = <function> defined =[C]:-1
format = <function> defined =[C]:-1
GetSpellInfo = nil

local GetSpellInfo
do
	if _G.GetSpellInfo then
		GetSpellInfo = _G.GetSpellInfo
	elseif _G.C_Spell and _G.C_Spell.GetSpellInfo then
		GetSpellInfo = _G.C_Spell.GetSpellInfo
	end
end

Added that to LibPlayerSpells-1.0..lua to stop the error. This will work for this particular case as the method is only used to do a simple "spell exists" check.

For a compatibility layer for classic clients it would need to extract the fields from the table C_Spell.GetSpellInfo returns and return them as an argument list.

I made the lib not load in classic, thanks