title: fs.createReadStream is undefined
body: <p>So originally I was trying to use google cloud node client to do something.
  Then the error </p>
  
  <pre><code>Unhandled Rejection (TypeError): fs.createReadStream is not a function
  </code></pre>
  
  <p>keep showing up. </p>
  
  <p>Here's the code snippet in "google-auth-library" that's been causing this</p>
  
  <pre><code>const fs = require("fs");
  ...
  const filePath = path.resolve(this.keyFilename);
  const stream = fs.createReadStream(filePath);
  await this.fromStreamAsync(stream, this.clientOptions);
  </code></pre>
  
  <p>I tried to print out fs and fs.createReadStream, and it shows fs is an object and createReadStream is of type undefined.</p>
  
  <pre><code>const fs = require("fs");
  
  console.log( "createReadStream type...");
  console.log( typeof fs.createReadStream );
  </code></pre>
  
  <p>The node version is v12.13.1, and I am running a react app initialized by create-react-app on Chrome. </p>
  
  <p>Can anyone tell me how to resolve this?</p>