const validateSchema = process.webpackModule.validateSchema;
^ TypeError: Cannot read property "validateSchema" of undefined
at Object. (E:wampwamp64wwwKaoyannode_moduleswebpack-clibinconvert-argv.js:7:46)

//webpackconfig.js
const webpack = require("webpack");
const path = require("path");
const UglifyJSPlugin = require("uglifyjs-webpack-plugin");
const HtmlWebpackPlugin = require("html-webpack-plugin");
const CleanWebpackPlugin = require("clean-webpack-plugin");
module.exports = {
  module: {
    rules: [
      {
        test: /\.js$/,
        exclude: /node_modules/,
        loader: "babel-loader"
      },
      {
        test: /\.(scss|css)$/,

        use: [
          {
            loader: "style-loader"
          },
          {
            loader: "css-loader"
          },
          {
            loader: "sass-loader"
          }
        ]
      }
    ]
  },
  plugins: [
    new CleanWebpackPlugin(["dist"]),
    new UglifyJSPlugin(),
    new HtmlWebpackPlugin({ title: "kaoyan", template: "./index.html" })
  ],
  entry: "./src/index",

  output: {
    filename: "[name].[chunkhash].js",
    chunkFilename: "[name].[chunkhash].js",
    path: path.resolve(__dirname, "dist")
  }
};

{
  "name": "kaoyan",
  "version": "1.0.0",
  "description": "kaoyan app",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "webpack-dev-server --mode=development --open"
  },
  "author": "Renkosky",
  "license": "ISC",
  "devDependencies": {
    "babel-core": "^6.26.3",
    "babel-loader": "^7.1.4",
    "babel-preset-env": "^1.7.0",
    "babel-preset-react": "^6.24.1",
    "clean-webpack-plugin": "^0.1.19",
    "html-webpack-plugin": "^3.2.0",
    "webpack": "^4.10.2",
    "webpack-cli": "^3.0.0",
    "webpack-dev-server": "^3.1.4"
  },
  "dependencies": {
    "css-loader": "^0.28.11",
    "node-sass": "^4.9.0",
    "react": "^16.4.0",
    "react-dom": "^16.4.0",
    "sass-loader": "^7.0.2",
    "style-loader": "^0.21.0",
    "uglifyjs-webpack-plugin": "^1.2.5"
  }
}

I remember that if the dev-server behavior is not modified in the configuration, there is no need to add the relevant configuration of dev-server, but somehow the error is reported. If you know, please let me know. Thank you very much!