title: Path must be a string. Received undefined
body: <p>When I create React App, I counter an error(image below).
  I use npm (v6.4), node (v8.9).</p>
  <p><a href="https://i.stack.imgur.com/qDk7G.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qDk7G.png" alt="enter image description here" /></a></p>
  <p>Can someone guide me?</p>