GetPlayerAuraBySpellID doesn't exist in classic. According to WoWPedia it wasn't added until Shadowlands.

The check at the top of handlers/config.lua now fails (https://github.com/kemayo/wow-handynotes-handler/blob/823b5b1e12b311b40531fde743e3e6b3b661a066/config.lua#L4):

-- compatibility between 10.0.0 and classic
local GetPlayerAuraBySpellID = _G.GetPlayerAuraBySpellID or C_UnitAuras.GetPlayerAuraBySpellID

Since _G.GetPlayerAuraBySpellID is nil, WoW tries to load C_UnitAuras.GetPlayerAuraBySpellID which fails immediately because C_UnitAuras doesn't exist in classic, either.

IIRC, detecting auras by spell names or IDs in classic requires iterating with UnitAura

To be fair, it's mostly an issue because C_UnitAuras doesn't exist on classic either.

To be fair, it's mostly an issue because C_UnitAuras doesn't exist on classic either.

Yeah, sorry, I hit a key combo that submitted the issue before I finished.

Regardless, checking for GetPlayerAuraBySpellID is good for Shadowlands vs. Dragonflight, but won't do anything for classic.

Right now in classic, the addon throws an error as soon as you load in. I'm guessing it would've thrown an error previously if the player were ever looking at a map where an icon depending on an aura being present or not present.

I'm guessing it would've thrown an error previously if the player were ever looking at a map where an icon depending on an aura being present or not present.

Yeah, it would have before -- there's just nothing in Wrath that needs that, so leaving retail code in there was perfectly fine for it.