title: Angular material: SassError: Invalid CSS after “@include mat”: expected 1 selector or at-rule, was “.core();”
body: <p>Angular version : 12
  npm : 6.13.1
  node :12.14.1</p>
  <p>Getting below error when building the application.</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>  /src/abc.scss - Error: Module build failed (from ./node_modules/mini-css-extract-plugin/dist/loader.js):
  [1] ModuleBuildError: Module build failed (from ./node_modules/sass-loader/dist/cjs.js):
  [1] SassError: Invalid CSS after "@include mat": expected 1 selector or at-rule, was ".core();"
  [1]         on line 8 of src/mv-app-theme.scss
  [1] &gt;&gt; @include mat.core();
  [1]    ---------^
  [1]
  [1]     at processResult (D:\project\node_modules\webpack\lib\NormalModule.js:676:19)
  [1]     at D:\project\node_modules\webpack\lib\NormalModule.js:778:5
  [1]     at D:\project\node_modules\loader-runner\lib\LoaderRunner.js:399:11
  [1]     at D:\project\node_modules\loader-runner\lib\LoaderRunner.js:251:18
  [1]     at context.callback (D:\project\node_modules\loader-runner\lib\LoaderRunner.js:124:13)
  [1]     at Object.callback (D:\project\node_modules\sass-loader\dist\index.js:54:7)
  [1]     at Object.done [as callback] (D:\project\node_modules\neo-async\async.js:8069:18)
  [1]     at options.error (D:\project\node_modules\node-sass\lib\index.js:294:32)</code></pre>
  </div>
  </div>
  </p>
  <p>Then I removed node-sass, now getting different error, Any idea?</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code> (node:19948) UnhandledPromiseRejectionWarning: TypeError: MessagePort was found in message but not listed in transferList
  [1]     at new Worker (internal/worker.js:144:17)
  [1]     at SassWorkerImplementation.createWorker (D:\project\node_modules\@angular-devkit\build-angular\src\sass\sass-service.js:96:24)
  [1]     at SassWorkerImplementation.render (D:\project\node_modules\@angular-devkit\build-angular\src\sass\sass-service.js:62:40)
      at Object.loader (D:\project\node_modules\sass-loader\dist\index.js:46:3)</code></pre>
  </div>
  </div>
  </p>