please post the stacktrace so I can see what kind of error it is.
I really don't expect an error would happen there if the salt is empty because the only difference when using a salt is that it is concatenated with the password before encrypting, and then for decrypting we the decrypted password will still have the salt concatentated to it, so we then replace it with an empty string.
So the only error I could see is if it causes an error to replace empty string with empty string. So please post the error details so I can understand what is happening.
Thanks,
Joe