title: Create-React-App deployment to Heroku failed with ` react-scripts: not found`
body: <p>We're developing a ReactJS application using Create-React-App, that is served from our Node/Express server that also serves API's. We deploy the whole server to Heroku using node/JS buildpack and trying to get the CRA build step <code>npm run build</code> in <code>postinstall</code> script from the node <code>package.json</code> file as suggested by @mars <a href="https://github.com/mars/create-react-app-buildpack/issues/32" rel="noreferrer">in this issue</a>. </p>
  
  <p>The issue is that Heroku deployment is failing with this error. Note that this error happen to me sometime locally but then a <code>npm install</code> from the web_app is solving the issue, but not when run in Heroku. I have two related questions:</p>
  
  <ol>
  <li>How to deploy to Heroku a Node/Express app that serves both APIs and a Create-React-App application? I can commit my build directory but this is really not the right way.</li>
  <li>Why the react-scripts are disappearing and I have to run multiple times the <code>npm install</code>. </li>
  </ol>