Creating user without password succeeds despite error

Created by: beyang

When creating a users with src user create, if a password is not provided, then an error is printed, but the user is created without a password anyway.

Repro:

$ src user create johndoe
rpc error: code = 6 desc = "account \"johndoe\" already exists"
$ src user create johndoe
rpc error: code = 6 desc = "account \"johndoe\" already exists"

Expected: the user should not be created if no password is specified.