title: "Could not find a required file" on `yarn start`
body: <p>I set up a <code>create-react-app</code> and I'm trying to run App.js on localhost, but upon doing <code>yarn start</code> I get the following error message:</p>
  
  <pre><code>22:23 $ yarn start
  yarn run v1.3.2
  $ react-scripts start
  Could not find a required file.
    Name: index.html
    Searched in: /Users/-----/Desktop/---/----/hw/HW-REPO/hw-name/public
  error Command failed with exit code 1.
  </code></pre>
  
  <p>I'd already installed yarn with <code>yarn install</code>, so I'm not sure if there's something wrong with my code or with the file structure.</p>
  
  <p>Here's the file structure:</p>
  
  <pre><code>app-name
   -client
     --public
       ---index.html
       ---manifest.json
     --src
       ---Components
          ----various folders
       ---App.js
       ---App.test.js
       ---index.js
   -database
   -model
   -gitignore
   -package-lock.json
   -package.json
   -server.js
   -yarn.lock
  </code></pre>