title: Javascript file cause React (Typescript) fail to start
body: <p>I have a React project with Typescript. One day I create a javascript file in <code>src/</code> and then my React app failed to start on localhost. Any explanation about this would be appriciated.<br />
  <strong>Evironment</strong>: Node 16.13.1<br />
  <strong>Step to reproduce</strong>:</p>
  <pre><code>git clone git@github.com:manaclan/fun-pms-frontend.git
  cd fun-pms-frontend
  git checkout vinhngo
  </code></pre>
  <p>Inside package.json remove:</p>
  <pre><code>&quot;@types/react-facebook-login&quot;: &quot;^4.1.4&quot;
  &quot;react-facebook-login&quot;: &quot;^4.1.1&quot;
  </code></pre>
  <p>Then <code>npm install</code> and <code>npm start</code> will notify that localhost:3000 failed to connect. Removing <code>src/setupProxy.js</code> will make the server start as normal</p>