Ugly promise

promise.js

var validateUser = function(user) {
  return new Promise(function(resolve, reject) {
    var validationError = c.validateFields(user, newUserRequiredFields, newUserAllowedFields);
    if (validationError) {
      reject(validationError);
    } else {
      checkUserExistence(user.username).then(resolve).catch(reject);
    }
  });
};

// Pretty promise
routes.validateUser = function(user) {
  var validationError = c.validateFields(user, newUserRequiredFields, newUserAllowedFields);
  return validationError ? Promise.reject(validationError)
                         : checkUserExistence(user.username);
};