const path = require('path');

const HtmlWebPackPlugin = require('html-webpack-plugin');
const MiniCssExtractPlugin = require("mini-css-extract-plugin");

module.exports = {
  entry: {
    index: ['./src/index.css', './src/index.js']
  },
  node: false,
  output: {
    path: path.join(__dirname, 'dist'),
    chunkFilename: 'chunks/[id].js'
  },
  devServer: {
    static: path.join(__dirname, 'dist'),
    compress: true,
    port: 3001,
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        enforce: "pre",
        use: ["source-map-loader"],
      },
      {
        test: /\.css$/,
        use: [
          MiniCssExtractPlugin.loader,
          'css-loader'
        ]
      },
    ]
  },
  plugins: [
    new HtmlWebPackPlugin({
      title: 'ArcGIS API  for JavaScript',
      template: './public/index.html',
      filename: './index.html',
      chunksSortMode: 'none',
      inlineSource: '.(css)$'
    }),
    new MiniCssExtractPlugin({
      filename: "[name].[chunkhash].css",
      chunkFilename: "[id].css"
    })
  ]
};

const path = require('path');

const HtmlWebPackPlugin = require('html-webpack-plugin');
const MiniCssExtractPlugin = require("mini-css-extract-plugin");

module.exports = {
  entry: {
    index: ['./src/index.css', './src/index.js']
  },
  node: false,
  output: {
    path: path.join(__dirname, 'dist'),
    chunkFilename: 'chunks/[id].js',
    clean: true
  },
  devServer: {
    static: './dist',
    compress: true,
    port: 3001,
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        enforce: "pre",
        use: ["source-map-loader"],
      },
      {
        test: /\.css$/,
        use: [
          MiniCssExtractPlugin.loader,
          'css-loader'
        ]
      },
    ]
  },
  plugins: [
    new HtmlWebPackPlugin({
      title: 'ArcGIS API  for JavaScript',
      template: './public/index.html',
      filename: './index.html',
      chunksSortMode: 'none',
      inlineSource: '.(css)$'
    }),
    new MiniCssExtractPlugin({
      filename: "[name].[chunkhash].css",
      chunkFilename: "[id].css"
    })
  ]
};

--- 
+++ 
@@ -10,11 +10,10 @@
   node: false,
   output: {
     path: path.join(__dirname, 'dist'),
-    chunkFilename: 'chunks/[id].js',
-    clean: true
+    chunkFilename: 'chunks/[id].js'
   },
   devServer: {
-    static: './dist',
+    static: path.join(__dirname, 'dist'),
     compress: true,
     port: 3001,
   },
Update webpack static, remove webpack clean so dist builds work again.
