title: You seem to not be depending on "@angular/core" and/or "rxjs". This is an error
body: <p>When i run the <code>ng serve -o</code> command in my angular project I get the following error:
  You seem to not be depending on <em>@angular/core</em> and/or <em>rxjs</em>. This is an error.</p>
  
  <p>Here are my versions:</p>
  
  <ul>
  <li>node -v --> 10.6.0 </li>
  <li>npm -v --> 6.2.0</li>
  </ul>