我正在使用yarn设置react项目的webpack，出现以下错误：
./src/app.js 67中的错误：6模块解析失败：意外标记（67：6）您可能需要适当的加载程序来处理此文件类型，当前未配置加载程序来处理此文件。请参阅https://webpack.js.org/concepts#loaders "wdm“：无法编译。
webpack.config.js

const path = require("path");

module.exports = {
    entry: "./src/app.js",
    output: {
        path: path.join(__dirname, 'public'),
        filename: 'bundle.js'
    },
    module:{
        rules:[{
            loader: 'babel-loader',
            test: '/\.(js|jsx)$/',
            exclude: /node_modules/
        }]
    },
    devtool: 'cheap-module-eval-source-map',
    devServer: {
        contentBase: path.join(__dirname, 'public')
    }
}

.babelrc
{
    "presets": ["env", "react","@babel/preset-env"],
    "plugins": [
        "transform-class-properties"
    ]
}

package.json

{
  "name": "react",
  "version": "1.0.0",
  "main": "index.js",
  "license": "MIT",
  "scripts": {
    "serve": "live-server public/",
    "build": "webpack",
    "dev-server": "webpack-dev-server"
  },
  "dependencies": {
    "babel-cli": "6.24.1",
    "babel-core": "6.25.0",
    "babel-plugin-transform-class-properties": "6.24.1",
    "babel-preset-env": "1.5.2",
    "babel-preset-react": "6.24.1",
    "live-server": "^1.2.1",
    "react": "^16.9.0",
    "react-dom": "^16.9.0",
    "webpack": "^4.39.3",
    "webpack-dev-server": "^3.8.0"
  },
  "devDependencies": {
    "@babel/core": "^7.6.0",
    "babel-loader": "^8.0.6",
    "webpack-cli": "^3.3.8"
  }
}