you have this error when you put a Armor Set into your action bar.
What helps is if you set a macro for it, something like:
/equipset [nobtn:2] SETNAME
/run if GetMouseButtonClicked()=="RightButton" then SaveEquipmentSet("SETNAME") end
I did not test it yet. But it should work.
Replace "SETNAME" 2 times with your armor set name.
When you left click it, or just use the hotkey like 2 3 or whatever, it will equip the set.
IF you manually right click it with your mouse, it will SAVE the set instead :)
And when you have this macro, the addon will not complain anymore about having an armor set in the action bar. So you solve two things at the same time :)
I hope this helps you.
Here's the API for it if you need further informations: