修复cert报错

plugins/http.js

@@ -22,7 +22,7 @@ const get = async (path, data, payload = {}) => await request('get', path, data,
  * @param {object} payload 其他选项
  * @param {object} promise 返回一个 promise
  */
-const post = async (path, data = {}, payload = { config: {} }) => {
+const post = async (path, data = {}, payload = {}) => {
   let formData = ''
   for(const key in data) {
     if(data.hasOwnProperty(key)) {
@@ -32,7 +32,7 @@ const post = async (path, data = {}, payload = { config: {} }) => {
   }
   formData = formData.slice(0, formData.length - 1)
   let config = { headers: { 'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8' } }
-  if(payload.config.headers) config.headers = {
+  if(payload.config && payload.config.headers) config.headers = {
     ...config.headers,
     ...payload.config.headers,
   }