The slot system is severely outdated too simplistic. There is not enough data to properly keep track of slots, and this makes them buggy and inconsistent. Here are the new requirements for slots:

• A new ID system so that every single slot can have a unique id, which will make upgrades easier.
• New logic for which types of items it can accept.
• Rework the slot container to better handle mutability, through the new unique id's of the slots.