Scroll of Warp not consumed if it is dropped or its inventory slot changes

[FM-96]

Steps to reproduce

1. Activate an attuned Scroll of Warp.
2. During the teleport delay either drop the used Scroll on the ground, or just move it to a different slot in your inventory.
3. The teleport will go through, but the Scroll will not be consumed. If it was dropped, it remains on the floor. If it was moved to a different inventory slot, it remains in that slot.

Proposed solution

I'm not familiar with Spigot's API, so I don't know if it's easy/possible to keep track of an item after it's been moved.

An alternative solution would be that the teleport gets canceled if you stop holding the Scroll of Warp during the delay (just like if you step off a teleporter). Especially when dropping the Scroll entirely, this would make more sense to me than the Scroll you're no longer holding successfully teleporting you.

Another alternative would be to consume the Scroll of Warp immediately upon starting the teleport. If you don't want the teleport to be cancelable, this seems like the easiest solution.