Fixed: "Candy.Core.getRoom(roomJid).getUser() is null" when you destroy the room

I have created a method to destroy the entire room, and with that, I found an error that the User its null, affecting the "Leave" method.

To reproduce:
- Create a room
- Send the stanza to destroy the room

Expected:
- Candy gets disconnected

Actual:
- An error is shown in the console: "Candy.Core.getRoom(roomJid).getUser() is null"