Wrong errors for unregistered attributes when using traits

[blakewest]

When adding an attribute through a trait... such as...

Replicator
  .define('user', {
    name: "Joe Bob"
  }
 .trait("withEmail", {
    email: function(attrs, i) {
      return attrs.name + "@gmai.com";
    }
  }

If I then try to do Replicator.build('user', {email: "blah@gmail.com"}), then it throws an error. It shouldn't.