title: puppeteer trouble. Or, at least, javascript trouble; you decide, please
body: <p>Can someone please explain what might be going wrong here:</p>
  <pre><code>await page.click('some-selector-that-devtools-confirms-is-definitely-there')
  let peeps = await page.evaluate(() =&gt;
      {
          document.querySelector('some-selector-that-devtools-confirms-is-definitely-there')
      }
  );
  console.log('classes: '+peeps.classList)
  </code></pre>
  <p>I've tried page.wait...., to no avail, same error</p>
  <p>Error</p>
  <pre><code>TypeError: Cannot read property 'classList' of undefined
  </code></pre>
  <p>Incidentally, is there a best practice for finding out if an element has a certain css class?</p>