Plugin causes webpack to throw on incremental compile (webpack 5 - watch mode)

[fuzing]

Expected behaviour

Should compile cleanly

Current behaviour

Plugin causes webpack (5) to throw/crash on incremental compile while in watch mode. Initial compile seems to run fine, but update to source code that results in attempt to incrementally recompile causes the following error:

TypeError: Cannot read property 'get' of undefined
    at /home/someone/project/node_modules/html-webpack-plugin/lib/compiler.js:341:38
    at Array.some (<anonymous>)
    at isChildCompilerCacheOutdated (/home/someone/project/node_modules/html-webpack-plugin/lib/compiler.js:340:59)
    at Object.hasOutDatedTemplateCache (/home/someone/project/node_modules/html-webpack-plugin/lib/compiler.js:321:16)
    at /home/someone/project/node_modules/html-webpack-plugin/index.js:135:25
    at Hook.eval [as call] (eval at create (/home/someone/project/node_modules/webpack/node_modules/tapable/lib/HookCodeFactory.js:19:10), <anonymous>:5:1)
    at Compiler.newCompilation (/home/someone/project/node_modules/webpack/lib/Compiler.js:857:30)
    at /home/someone/project/node_modules/webpack/lib/Compiler.js:898:29
    at Hook.eval [as callAsync] (eval at create (/home/someone/project/node_modules/webpack/node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:4:1)
    at Compiler.compile (/home/someone/project/node_modules/webpack/lib/Compiler.js:893:28)
    at /home/someone/project/node_modules/webpack/lib/Watching.js:111:19
    at Hook.eval [as callAsync] (eval at create (/home/someone/project/node_modules/webpack/node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:4:1)
    at /home/someone/project/node_modules/webpack/lib/Watching.js:65:33
    at /home/someone/project/node_modules/webpack/lib/HookWebpackError.js:69:3
    at Hook.eval [as callAsync] (eval at create (/home/someone/project/node_modules/webpack/node_modules/tapable/lib/HookCodeFactory.js:33:10), <anonymous>:4:1)
    at Cache.endIdle (/home/someone/project/node_modules/webpack/lib/Cache.js:140:22)
    at Watching._go (/home/someone/project/node_modules/webpack/lib/Watching.js:63:23)
    at Watching._invalidate (/home/someone/project/node_modules/webpack/lib/Watching.js:238:9)
    at /home/someone/project/node_modules/webpack/lib/Watching.js:202:11
    at Watchpack.<anonymous> (/home/someone/project/node_modules/webpack/lib/node/NodeWatchFileSystem.js:85:4)
    at Object.onceWrapper (events.js:300:26)
    at Watchpack.emit (events.js:210:5)
    at Watchpack._onTimeout (/home/someone/projectg/node_modules/webpack/node_modules/watchpack/lib/watchpack.js:297:8)
    at listOnTimeout (internal/timers.js:531:17)
    at processTimers (internal/timers.js:475:7)

Environment

Tell us which operating system you are using, as well as which versions of Node.js, npm, webpack, and html-webpack-plugin. Run the following to get it quickly:
node v13.2.0
ubuntu 18.04
npm 6.13.1
webpack 5.0.0-beta.7
html-webpack-plugin 4.0.0-beta.11

Config

const webpack = require('webpack');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');
const appRoot = require('app-root-path');

// place where our views will go
const VIEWS_DEST_DIR = appRoot + '/dist/backend/views';

// place where our Handlebars view root is
const HANDLEBARS_VIEWS = appRoot + '/src/backend/views';

module.exports = {

  mode: 'development',

  entry: {app: './src/frontend/entrypoint/app.js'},

  output: {
    path: appRoot + '/dist/frontend-serve',
    publicPath: '/',
    filename: '[name].js',
  },


  resolve: {
    modules: [`${appRoot}/src`, 'node_modules'],

    extensions: ['.mjs', '.js', '.jsx'],

  },

  module: {
    rules: [
      // .mjs needed for https://github.com/graphql/graphql-js/issues/1272
      {
        test: /\.mjs$/,
        include: /node_modules/,
        type: 'javascript/auto'
      },
      // All files with a '.js' or '.jsx' extension will be handled by 'babel-loader'
      {
        test: /\.jsx?$/,
        exclude: [/node_modules/],
        use: {
          loader: 'babel-loader',
          options: {
            presets: [
              ['@babel/preset-env', {
                targets: {"browsers": ["last 2 versions"]},
                modules: false,         // don't let the "env" preset mess with module imports (tree-shaking)
              },
              ],
              '@babel/preset-react', '@babel/preset-flow'
            ],

  
            plugins: [
              "babel-plugin-styled-components",
              [
                "@babel/plugin-transform-runtime",
                {
                  "helpers": true,
                  "regenerator": true,
                  "useESModules": false,
                }
              ],
              ["@babel/plugin-proposal-class-properties", {"loose": false}],
            ],
          }
        }
      },

      {
        test: /\.html$/,
        use: {
          loader: 'html-loader'
        }
      },

      {
        test: /\.(png|jpe?g|gif|svg|woff|woff2|ttf|eot|ico)$/,
        use: {
          loader: 'file-loader?name=assets/[name].[ext]'
        }
      },

      {
        test: /\.css$/,
          use: [
            MiniCssExtractPlugin.loader,
            "css-loader",
          ],
      },

      {
        test: /\.(sass|scss)$/,
        use: [
          MiniCssExtractPlugin.loader,
          'css-loader', 'sass-loader',
        ],
      },
    ]
  },

  plugins: [
    //
    // our app's page
    //
    new HtmlWebpackPlugin({
      template: 'src/backend/views/pages/app.hbs',
      filename: `${VIEWS_DEST_DIR}/app.hbs`,
    }),

    // in production we cache-bust
    new MiniCssExtractPlugin({ filename: '[name].css' }),

  ],

};

[vankop]

Same issue webpack-contrib/stylelint-webpack-plugin#187

New API for watching files: webpack/webpack#9679

[kenotron]

Seems very much like the same thing as #1292

[jantimon]

Duplicate of #1129