title: no service-worker.js file after npm run build in react
body: <p>After running <code>npm run dev</code> no service-worker.js file in build folder.</p>
  <blockquote>
  <p>I'm also changed <code>serviceWorker.register()</code> in index.js
  <br>I'm also using firebase in this project.</p>
  </blockquote>
  <p>Here is <em><strong>package.json</strong></em> file</p>
  <pre><code>{
    &quot;name&quot;: &quot;movie&quot;,
    &quot;version&quot;: &quot;0.1.0&quot;,
    &quot;private&quot;: true,
    &quot;dependencies&quot;: {
      &quot;@testing-library/jest-dom&quot;: &quot;^4.2.4&quot;,
      &quot;@testing-library/react&quot;: &quot;^9.5.0&quot;,
      &quot;@testing-library/user-event&quot;: &quot;^7.2.1&quot;,
      &quot;axios&quot;: &quot;^0.20.0&quot;,
      &quot;email-verifier&quot;: &quot;^0.4.1&quot;,
      &quot;firebase&quot;: &quot;^7.24.0&quot;,
      &quot;history&quot;: &quot;^5.0.0&quot;,
      &quot;react&quot;: &quot;^16.13.1&quot;,
      &quot;react-dom&quot;: &quot;^16.13.1&quot;,
      &quot;react-lottie&quot;: &quot;^1.2.3&quot;,
      &quot;react-router-dom&quot;: &quot;^5.2.0&quot;,
      &quot;react-scripts&quot;: &quot;^4.0.0&quot;
    },
    &quot;scripts&quot;: {
      &quot;start&quot;: &quot;react-scripts start&quot;,
      &quot;build&quot;: &quot;react-scripts build&quot;,
      &quot;test&quot;: &quot;react-scripts test&quot;,
      &quot;eject&quot;: &quot;react-scripts eject&quot;
    },
    &quot;eslintConfig&quot;: {
      &quot;extends&quot;: &quot;react-app&quot;
    },
    &quot;browserslist&quot;: {
      &quot;production&quot;: [
        &quot;&gt;0.2%&quot;,
        &quot;not dead&quot;,
        &quot;not op_mini all&quot;
      ],
      &quot;development&quot;: [
        &quot;last 1 chrome version&quot;,
        &quot;last 1 firefox version&quot;,
        &quot;last 1 safari version&quot;
      ]
    },
    &quot;devDependencies&quot;: {
      &quot;@types/react-router-dom&quot;: &quot;^5.1.6&quot;
    }
  }
  
  </code></pre>
  <p>After deploy in firebase ,I got this error.</p>
  <blockquote>
  <p>serviceWorker.js:97
  Error during service worker registration: DOMException: Failed to register a ServiceWorker for scope ('https://<em><strong>.web.app/') with script ('https://</strong></em>*.web.app/service-worker.js'):
  The script has an unsupported MIME type ('text/html').</p>
  </blockquote>
  <p><a href="https://i.stack.imgur.com/zzaFD.png" rel="noreferrer"><img src="https://i.stack.imgur.com/zzaFD.png" alt="enter image description here" /></a></p>