It seems like GetLootSlotInfo changed.
7.3.5
Lua Code:
texture, item, quantity, quality, locked, isQuestItem, questId, isActive = GetLootSlotInfo(slot);
8.0
Lua Code:
texture, item, quantity, currencyID, quality, locked, isQuestItem, questId, isActive = GetLootSlotInfo(slot);
This should work.
Lua Code:
local locked, isQuestItem = select(6, GetLootSlotInfo(i))
And for UnitAura they got rid of the 2nd return value (rank)