Errors don't appear because the argument is in quotes. The computer recognizes it as a proper argument even though it's not. (It still should always be in quotes though)
I'm trying to create a custom player-like mob (so a custom mob that looks exactly like a player and walks the same way), but I don't know how to make it be a player model instead of a zombie model, or how to change what sounds it makes (preferably to player sounds.) Could somebody help me?