When you are manually typing the characters and you mistakenly type another character and you send it then the person send the coin and coin entered another person address then your fund is gone.
This is unlikely to happen thanks to the built-in checksum. If you mistype one or few characters then you will high likely end up with an invalid address. Any decent wallet software will notify the user if the checksum fails and will not let him create the transaction.
Even if you use a faulty wallet which will let you broadcast a transaction that sends coins to an invalid address, the network will reject it. So, the chances of losing coins because of this are really tiny.