title: why am I getting Unknown option: '--output-hashing' angular 9
body: <p>we have updated our build command from</p>
  <p>&quot;start&quot;: &quot;ng serve --configuration=dev --aot --o&quot;,</p>
  <p>to</p>
  <p>&quot;start&quot;: &quot;ng serve --configuration=dev --aot --output-hashing=all&quot;,</p>
  <p>but when i build i am getting the below error</p>
  <blockquote>
  <p>Unknown option: '--output-hashing' npm ERR! code ELIFECYCLE npm ERR!
  errno 1 npm ERR! client-app@0.0.0 start: <code>ng serve --configuration=dev --aot --output-hashing=all</code> npm ERR! Exit status 1 npm ERR! npm ERR! Failed at the client-app@0.0.0 start script. npm ERR! This is probably
  not a problem with npm. There is likely additional logging output
  above.</p>
  </blockquote>
  <p>any idea why and how to solve</p>