React Axios to Rails Knock

我正在尝试使用React前端中的以下函数将axios的POST请求发送到Rails API：

export function registerUser({ name, email, password }) {
    var postdata = JSON.stringify({
      auth: {
        name, email, password
        }
      });
    return function(dispatch) {
      axios.post(`${API_URL}/user_token`, postdata )
      .then(response => {
        cookie.save('token', response.data.token, { path: '/' });
        dispatch({ type: AUTH_USER });
        window.location.href = CLIENT_ROOT_URL + '/dashboard';
      })
      .catch((error) => {
        errorHandler(dispatch, error.response, AUTH_ERROR)
      });
    }
  }

Knock gem期望以下格式的请求：

{"auth": {"email": "foo@bar.com", "password": "secret"}}

我当前的函数似乎生成正确的格式（在浏览器devtools中检查请求），但我收到以下错误：

未捕获（承诺）错误：对象作为React子对象无效（找到：具有键{data，status，statusText，headers，config，request}的对象） . 如果您要渲染子集合，请使用数组，或使用React附加组件中的createFragment（object）包装对象 . 检查Register的render方法 .

class Register extends Component {
  handleFormSubmit(formProps) {
    this.props.registerUser(formProps);
  }

  renderAlert() {
    if(this.props.errorMessage) {
      return (
        <div>
          <span><strong>Error!</strong> {this.props.errorMessage}</span>
        </div>
      );
    }
  }

  render() {
    const { handleSubmit } = this.props;

    return (
      <form onSubmit={handleSubmit(this.handleFormSubmit.bind(this))}>
      {this.renderAlert()}
      <div className="row">
        <div className="col-md-6">
          <label>Name</label>
          <Field name="name" className="form-control" component={renderField} type="text" />
        </div>
      </div>
        <div className="row">
          <div className="col-md-12">
            <label>Email</label>
            <Field name="email" className="form-control" component={renderField} type="text" />
          </div>
        </div>
        <div className="row">
          <div className="col-md-12">
            <label>Password</label>
            <Field name="password" className="form-control" component={renderField} type="password" />
          </div>
        </div>
        <button type="submit" className="btn btn-primary">Register</button>
      </form>
    );
  }
}