Wrong id's can happen to anyone.
Even happened for Simon.
Even it happened to me when i was fully got mad because of High Ddos attack.
I also prefer counter's suggestion but this isnt a bug.
The problem is they didnt add no id error report.
But it works for reason there in /ban [id] [reason].
If we didnt type reason,we cant ban.
So i think it is possible to add id error message .