Ugh, that's an old bug in aura.lua, I forgot about it, cuz I never use default aura button constructor.
Default oUF aura buttons and few other frames have no names assigned, and it causes /fstack errors.
For now just do not use default constructor. You'll have to create your own create button function, you can pretty much copy-paste
existing one, and add names to all frames. And then override it this way:
Lua Code:
local function CreateAuraIcon(frame, index)
-- code here
end
f.Buffs.CreateIcon = CreateAuraIcon