title: Angular 8: No provider for MultilevelMenuService
body: <p>I have an angular8 project which I upgraded recently from angular7 on node: &quot;10.15.2&quot;,&quot;npm&quot;: &quot;6.14.5&quot;</p>
  <p>I'm using the following plugin</p>
  <p><a href="https://www.npmjs.com/package/ng-material-multilevel-menu" rel="nofollow noreferrer">https://www.npmjs.com/package/ng-material-multilevel-menu</a></p>
  <p>@4.12.2</p>
  <p>With <code>ng serve</code> the application works fine and the multilevel as expected.</p>
  <p>However I've installed angular ssr as described in <a href="https://angular.io/guide/universal" rel="nofollow noreferrer">universal</a> and when when I run with the command:</p>
  <p><code>ng serve --prod --optimization=false</code></p>
  <p>or</p>
  <p><code>npm run build:ssr &amp;&amp; npm run serve:ssr</code></p>
  <p>I receive the following error:</p>
  <blockquote>
  <p>main.96f1c69496e6c439b888.js:29505 ERROR NullInjectorError: StaticInjectorError(AppModule)[ListItemComponent -&gt; MultilevelMenuService]:
  StaticInjectorError(Platform: core)[ListItemComponent -&gt; MultilevelMenuService]:
  NullInjectorError: No provider for MultilevelMenuService!</p>
  </blockquote>
  <p>I have made the following project in order to show the error I get which you can find in the link <a href="https://github.com/symeonmattes/angular8-ng-multilevel" rel="nofollow noreferrer">angular8-ng-multilevel</a></p>
  <p>Any ideas on how could I solve it?</p>
  <p>Thanks</p>