title: laravel-mix produces empty (0 bytes) .css files WITHOUT dynamic imports and .extract
body: <p>I'm getting empty .css files without using .extract and import()
  When I'm running <code>npm run dev</code></p>
  
  <p>My webpack.mix.js:</p>
  
  <pre><code>let mix = require('laravel-mix');
  mix.js('resources/assets/js/app.js', 'public/js').sourceMaps()
      .js('resources/assets/js/admin.js', 'public/js').sourceMaps()
      .sass('resources/assets/sass/app.scss', 'public/css')
      .sass('resources/assets/sass/admin.scss', 'public/css');
  
  mix.copyDirectory('resources/assets/img', 'public/img');
  </code></pre>
  
  <p>The strange thing here is that if I remove one of .js mixes it works. For example this works:</p>
  
  <pre><code>mix.js('resources/assets/js/app.js', 'public/js').sourceMaps()
      .sass('resources/assets/sass/app.scss', 'public/css')
      .sass('resources/assets/sass/admin.scss', 'public/css');
  </code></pre>
  
  <p>this also works:</p>
  
  <pre><code>mix.js('resources/assets/js/admin.js', 'public/js').sourceMaps()
      .sass('resources/assets/sass/app.scss', 'public/css')
      .sass('resources/assets/sass/admin.scss', 'public/css');
  </code></pre>
  
  <p>But I need to generate admin.js (or app.js) after that. Which is not very handy. 
  Any ideas what I'm doing wrong?</p>
  
  <p>My environment is:</p>
  
  <ul>
  <li>Laravel Mix Version: 5.0.0</li>
  <li>Node Version: 11.0.0</li>
  <li>NPM Version: 6.10.3</li>
  <li>OS: macOS High Siera  / Ubuntu 18.04 LTS</li>
  </ul>
  
  <p>I'm sure that I have no dynamic imports, because I'm upgrading from laravel-mix v.3. But also I checked my code. And if I have dynamic imports, none of my examples will work.</p>
  
  <p>EDIT: 
  I found that the problem is in my admin.js file which imports:</p>
  
  <pre><code>import router from './router'
  </code></pre>
  
  <p>and  in /router/index.js there is another import:</p>
  
  <pre><code>import routes from './routes.js'
  </code></pre>
  
  <p>and the problem seеms to be in routes.js file which looks like that:</p>
  
  <pre><code>const routes = [
      {
          path: '/',
          component: resolve =&gt; require(['../views/admin/dashboard/dashboard.vue'], resolve),
          meta: {
              title: "Dashboard",
          }
      },
  ];
  export default routes
  </code></pre>
  
  <p>But, I can't still explain where is the dynamic import here?!?!?
  Or how this works:</p>
  
  <pre><code>mix.js('resources/assets/js/admin.js', 'public/js').sourceMaps()
      .sass('resources/assets/sass/admin.scss', 'public/css');
  </code></pre>