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

其中 app.vue
<template>

<div id="app">
    <router-view/>
</div>

</template>

<script>

export default {
    name: 'App'
}

</script>

<style lang="less">

@import '~vux/src/styles/reset.less';

</style>

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({

el: '#app',
router,
components: { App },
template: '<App/>'

})

为啥报错啊