iview UI庫加載進度條如何使用？貼出代碼：負責路由的index.jsimport Vue from 'vue'import Router from 'vue-router'import iView from 'iview'import HelloWorld from '@/components/HelloWorld'Vue.use(Router)Vue.use(iView)// 路由加載條Router.beforeEach((transition) => {  iView.LoadingBar.start()  transition.next()})Router.afterEach((transition) => {  iView.LoadingBar.finish()})export default new Router({  routes: [    {      path: '/',      name: 'HelloWorld',      component: HelloWorld    }  ]})報錯截圖：第一次使用，有大佬給出一點意見嗎？