Vue 組件封裝發布到npm 報錯 Uncaught TypeError: Cannot read property 'toLowerCase' of undefined

Uncaught TypeError: Cannot read property 'toLowerCase' of undefined

原因是 沒有導出 export default { name:"Test" }  

index.js 文件

import Test from './src/main.vue'

Test.install = function (Vue) {

Vue.component(Test.name, Test

}

export default Test