bug(From BCD): Uncaught TypeError can'nt access property indexOf, n is undefined

To reproduce that use a direct url https://gchq.github.io/CyberChef/#recipe=From_BCD('',true,false,'Nibbles')&input=MTAwMA&oeol=VT, then as you can see

From BCD - TypeError in blob:https://gchq.github.io/7f68ce91-b78c-4bad-92a1-2f639f10c891 on line 2.<br><br>Message: can't access property "indexOf", n is undefined

the issue is simple issue the first parameter not checked is empty or not, that persists, because after that a code try to use indexOf in n, and simply n is undefined, will throw an error