If you add an "L" behind the ammount of XP, it will cause an error instead of adding ammout of level to the player.

Steps to reproduce:

1.  Create / open a new world with cheats ON.
2. Run the following command: /xp 10L @s

Expected Results:

• The command should gives yourself 10 levels.

Observed Results:

• The command isn't giving any level or experience to yourself, and an eror is given instead.