vue2.5.2引入组件库提示没有export default

Question

自己写了一个组件库，这个组件库在vue2.5.13的项目内可以正常运行。但是在vue2.5.2的项目内则会报错
"export 'default' (imported as 'install') was not found in './assets/test-ui'

/** index.js **/

import Vue from 'vue'
import * as form from './form';
const components = {
    ...form
}
const install = function (Vue, Option) {
     Object.keys(components).forEach((key) => {
        Vue.component(components[key].name, components[key])
    })
}

if (typeof window !== 'undefined' && window.Vue) {
    install(window.Vue);
  }

export default {
    install
}

/** package.json **/
"dependencies": {
    "deepmerge": "^3.2.0",
    "echart": "^0.1.3",
    "echarts": "^4.1.0",
    "vue": "^2.5.2",
    "vue-router": "^3.0.1"
  }

在项目内引用

/** main.js **/

import install from 'assets_js/util/test-ui';
Vue.use(install);