After Angular 6 update, ng build --prod yields "Error: Expected to find an ngsw-config.json configuration file" : <p>The update went fine, but now when I build, I get the following error.</p>

<blockquote>
  <p>Error: Expected to find an ngsw-config.json configuration file in the
  /Users/nathanielmay/Code/firebaseTest folder. Either provide one or
  disable Service Worker in your angular.json configuration file.</p>
</blockquote>

<p>I looked in my <code>angular.json</code> and found that on this line:</p>

<pre><code>"ngswConfigPath": "/src/ngsw-config.json",
</code></pre>

<blockquote>
  <p>Property ngswConfigPath is not allowed.</p>
</blockquote>

<p>I can't find an api for the new angular.json, but it seems as if I need to specify the path in a different way. </p>

<p><code>ng update @angular/pwa</code> didn't work either.</p>

<p>How can I resolve this error?</p>
