Cannot read property 'toLowerCase' of undefined

vue.esm.js?efeb:113 Uncaught TypeError: Cannot read property 'toLowerCase' of undefined
    at eval (webpack-internal:///./node_modules/vue/dist/vue.esm.js:114:38)
    at validateComponentName (webpack-internal:///./node_modules/vue/dist/vue.esm.js:1344:7)
    at Function.Vue.(anonymous function) [as component] (webpack-internal:///./node_modules/vue/dist/vue.esm.js:4876:11)
    at eval (webpack-internal:///./src/components/index.js:33:17)
    at Array.map ()
    at Object.install (webpack-internal:///./src/components/index.js:31:95)
    at Function.Vue.use (webpack-internal:///./node_modules/vue/dist/vue.esm.js:4750:22)
    at eval (webpack-internal:///./src/main.js:40:46)
    at Object../src/main.js (http://localhost:8080/app.js:3050:1)
    at __webpack_require__ (http://localhost:8080/app.js:679:30)

这个不是因为大小写的原因，而是组件中‘name’的值没有设置。

VM27721:1 ./src/components/public/Footer.vue
There are multiple modules with names that only differ in casing.
This can lead to unexpected behavior when compiling on a filesystem with other case-semantic.
Use equal casing. Compare these module identifiers:
* D:\yanPro\wshop\node_modules\vue-loader\index.js??ref--0!D:\yanPro\wshop\src\components\public\Footer.vue
    Used by 1 module(s), i. e.
    D:\yanPro\wshop\node_modules\babel-loader\lib\index.js!D:\yanPro\wshop\src\components\index.js
* D:\yanPro\wshop\node_modules\vue-loader\index.js??ref--0!D:\yanPro\wshop\src\components\public\footer.vue
    Used by 1 module(s), i. e.
    D:\yanPro\wshop\node_modules\babel-loader\lib\index.js!D:\yanPro\wshop\node_modules\vue-loader\lib\selector.js?type=script&index=0!D:\yanPro\wshop\src\App.vue
 @ ./src/components/public/Footer.vue
 @ ./src/components/index.js
 @ ./src/main.js
 @ multi (webpack)-dev-server/client?http://0.0.0.0:8080 webpack/hot/dev-server ./src/main.js

这里是警告，

 有多个模块的名称只在大小写上有所不同，

这可能导致在具有其他case语义的文件系统上编译时出现意外行为