title: webpack-dev-server cannot really compile main.js
body: <p><a href="https://github.com/chikadance/test-webpack/tree/webpack-dev-server-cannot-compile" rel="nofollow noreferrer">Here</a> is my project</p>
  
  <p>webpack-dev-server terminal output: </p>
  
  <pre><code>Built at: 05/22/2020 6:43:46 PM
                                        Asset       Size  Chunks                               Chunk Names
         8d6d49ad1bd332417f87.hot-update.json   46 bytes          [emitted] [immutable] [hmr]  
      main.8d6d49ad1bd332417f87.hot-update.js  334 bytes    main  [emitted] [immutable] [hmr]  main
  main.8d6d49ad1bd332417f87.hot-update.js.map  259 bytes    main  [emitted] [dev]              main
                                      main.js    383 KiB    main  [emitted]                    main
                                  main.js.map    434 KiB    main  [emitted] [dev]              main
  Entrypoint main = main.js main.8d6d49ad1bd332417f87.hot-update.js main.js.map main.8d6d49ad1bd332417f87.hot-update.js.map
  [./src/t.js] 70 bytes {main} [built]
      + 39 hidden modules
  ℹ ｢wdm｣: Compiled successfully.
  </code></pre>
  
  <p>I cannot find the main.js</p>
  
  <pre><code>roroco@roroco ~/Downloads/js/test-webpack $ du -ah|grep main.js
  4.0K    ./node_modules/os-browserify/main.js
  4.0K    ./node_modules/webpack-dev-server/lib/utils/createDomain.js
  4.0K    ./node_modules/timers-browserify/main.js
  12K ./node_modules/sockjs-client/lib/main.js
  </code></pre>