vue出现以下两个问题

Cannot find element: #app 和 Failed to mount component: template or render function not defined. 两个错误

其中 app.vue

main.js
import Vue from 'vue'
import App from './App'
import FastClick from 'fastclick'

import router from './router'
import VueCOOKIEs from 'vue-COOKIEs'
Vue.use(VueCOOKIEs);

FastClick.attach(document.body)

Vue.config.productiOnTip= false

/ eslint-disable no-new /
new Vue({

})

为啥报错啊