什么时候以及如何触发axios拦截器请求错误？

Question

有一个Axios

的示例

// Add a request interceptor
axios.interceptors.request.use(function (config) {
    // Do something before request is sent
    return config;
  }, function (error) {
    // Do something with request error
    console.log('error in request!' + error)
    // ===============================
    // ===============================
    // ===============================
    // Here's the Question, no error will enter here.
    // ===============================
    // ===============================
    // ===============================
    return Promise.reject(error);
  });

// Add a response interceptor
axios.interceptors.response.use(function (response) {
    // Any status code that lie within the range of 2xx cause this function to trigger
    // Do something with response data
    return response;
  }, function (error) {
    // Any status codes that falls outside the range of 2xx cause this function to trigger
    // Do something with response error
    return Promise.reject(error);
  });

嗨，大家好，没有错误的输入axios.interceptors.request.use(config, error)，所有errors都输入了axios.interceptors.response.use(config, error)

何时以及如何触发axios拦截器request错误？