const getSignupFormFieldErrors = fields => {
  let errors = {};
  if (typeof fields.username === "undefined") {
    errors.username = MISSING_FIELD;
  }
  if (typeof fields.email === "undefined") {
    errors.email = MISSING_FIELD;
  }
  if (typeof fields.password === "undefined") {
    errors.password = MISSING_FIELD;
  }
  if (typeof fields.passwordConfirmation === "undefined") {
    errors.passwordConfirmation = MISSING_FIELD;
  }
  return errors;
};