Change for ifempty specialized command, added new subvalue as maininv which will include slots from 1 to 36. So its a main inventory slots. Differently then inv value which includes offhand and armor slots
Now quickbar/maininv/subinv has option to include slot count you need in particular to be free. maininv-5 will require you to have 5 free slots in your main inventory, while subinv-10 will require to have 10 free slots in sub inventory and quickbar-3 will require you to have 3 free slots in quick bar. Example of usage: ifempty:maininv-3?!
Small fix related to possible issue with donate command