stacks to a slot, since stacks will commonly self delete, even if you add them to different slots. This is
because stack code does not respect slots, and I can't figure out a good way to fix that outside of this.
Also fixes like, a 2% chance unit test failure caused by a mob spawner that has a low percent chance to spawn a
miner with cash in both pockets. I hate god.
Co-authored-by: LemonInTheDark <58055496+LemonInTheDark@users.noreply.github.com>