问Uncaught : Vue.mixin不是函数

EN

app.js:2076 Uncaught TypeError: Vue.mixin is not a function
at Module../resources/js/app.js (app.js:2076:5)
at __webpack_require__ (app.js:34977:42)
at app.js:35142:64
at Function.__webpack_require__.O (app.js:35014:23)
at app.js:35144:53
at app.js:35146:12

require('./bootstrap');

window.Vue = require('vue')
import router from './router'
import vuex from './vuex'
import common from './common'
Vue.mixin(common)

Vue.component('mainapp', require('./app/mainapp.vue').default)
const app = new Vue({
    el: '#app', 
    router, 
    vuex
})

import Vue from 'vue'
import Router from 'vue-router'
Vue.use(Router)
import home from './app/website/home.vue'

const routes = [

    {
        path:'/',
        name : '/',
        component: home,
    } 
]

const router = new Router({
    mode:'history',
    routes
}) 

export default router;