It is possible to glitch your hand

The Bug

One can make it so that the player's hand displays instead of the item that is selected on the hotbar.

How to Reproduce:

1. Take one of any edible/drinkable item.
2. Continuously press the "Use/Place block" key.
3. After you've eaten/drank the item, switch to another item in your hotbar using the number keys (1-9) while still holding down the "Use/Place block" key.

-> You've selected an item in your hotbar but you're not holding it in your main hand 

How to Reproduce on Touch Screen: (from [Helper] osfanbuff63)

1. Take one of any item
2. Tap on the hotbar and elsewhere on the screen at the same time

-> You've selected an item in your hotbar but it is actually showing an empty hand