problem description
 webpack compiles vue file and keeps reporting errors 
 ERROR in. / src/app.vue 3:0 
 Module parse failed: Unexpected token (3:0) 
 You may need an appropriate loader to handle this file type. 
 | 
 | 
< template >
| < div class= "example" > {{msg}} < / div >
| < / template >
@. / src/index.js 4:0-28 8:18-21
  
the environmental background of the problems and what methods you have tried
I read a lot of answers on the Internet, but I didn"t solve them
related codes
/ / Please paste the code text below (do not replace the code with pictures)
 const path = require ("path"); 
 const VueLoaderPlugin = require (" vue-loader/lib/plugin"); 
 module.exprots = {
mode: "development",
entry: path.join(__dirname, "src/index.js"),
output: {
    path: path.resolve(__dirname, "dist"),
    filename: "bundle.js",
},
module: {
    rules: [
        {
            test: /\.vue$/,
            loader: "vue-loader",
            exclude: file => (
                /node_modules/.test(file) &&
                !/\.vue\.js/.test(file)
            )
        },
        {
            test: /\.js$/,
            loader: "babel-loader"
        },
        {
            test: /\.css$/,
            loader: "style-loader!css-loader"
        }
    ]
},
plugins: [
    new VueLoaderPlugin()
]}
related codes
app.vue
 < template > 
 < div class= "example" > {{msg}} < / div > 
 < / template > 
 < script > 
 export default {
 data () {
return {
  msg: "Hello world!"
}} 
} 
 < / script > 
 < style > 
 .example {
 color: red; 
} 
 < / style > 
related codes
 package.json file 
 {
 "name": "vue", 
 "version": "1.0.0", 
 "description": "", 
 "main": "index.js", 
 "scripts": {
"dev": "webpack --mode=development",
"test": "echo \"Error: no test specified\" && exit 1"}, 
 "author": "", 
 "license": "ISC", 
 "dependencies": {
"vue": "^2.5.22"}, 
 "devDependencies": {
"babel-loader": "^8.0.5",
"css-loader": "^2.1.0",
"node-pre-gyp": "^0.12.0",
"style-loader": "^0.23.1",
"vue-loader": "^15.5.1",
"vue-template-compiler": "^2.5.22",
"webpack": "^4.28.4",
"webpack-cli": "^3.2.1"} 
} 
related codes
 index.js 
 import Vue from "vue"; 
 import App from ". / app.vue"; 
new Vue ({
)el: "-sharproot",
components: { App },
template: "<App/>"});
