title: unhandled promise rejection: staticinjectorerror(t):MatRipple -> ElementRef]
body: <p>I recently upgraded to angular 6. On trying to load the app, I get this error:</p>
  
  <pre><code>Error: StaticInjectorError(t)[MatRipple -&gt; ElementRef]:
  StaticInjectorError(Platform: core)[MatRipple -&gt; ElementRef]:
  NullInjectorError: No provider for ElementRef!
  at t.get (main-client.js?v=uKfS6-YQlbK5hOKHois0Ghb7I_E4cHpAFDXv2Qk9aiw:78)
  at main-client.js?v=uKfS6-YQlbK5hOKHois0Ghb7I_E4cHpAFDXv2Qk9aiw:78
  at xt (main-client.js?v=uKfS6-YQlbK5hOKHois0Ghb7I_E4cHpAFDXv2Qk9aiw:78)
  at t.get (main-client.js?v=uKfS6-YQlbK5hOKHois0Ghb7I_E4cHpAFDXv2Qk9aiw:78)
  at main-client.js?v=uKfS6-YQlbK5hOKHois0Ghb7I_E4cHpAFDXv2Qk9aiw:78
  at xt (main-client.js?v=uKfS6-YQlbK5hOKHois0Ghb7I_E4cHpAFDXv2Qk9aiw:78)
  at t.get (main-client.js?v=uKfS6-YQlbK5hOKHois0Ghb7I_E4cHpAFDXv2Qk9aiw:78)
  at jo (main-client.js?v=uKfS6-YQlbK5hOKHois0Ghb7I_E4cHpAFDXv2Qk9aiw:383)
  at t.get (main-client.js?v=uKfS6-YQlbK5hOKHois0Ghb7I_E4cHpAFDXv2Qk9aiw:398)
  at Os (main-client.js?v=uKfS6-YQlbK5hOKHois0Ghb7I_E4cHpAFDXv2Qk9aiw:405)
  View_t_0 @ t.html:2
  </code></pre>
  
  <p>I dont know whats exactly wrong but after troubleshooting for sometime I discovered that the upgrade is having issues recognizing a angular material elements for example : mat-list-item.
  This was working properly before the upgrade. Whats going on?</p>