title: Whatsapp group chat invite link not working
body: <p>I have a button that links to a Whatsapp group chat via the group's invite links <code>https://chat.whatsapp.com/xxxxxxxxxxxxxxxxxxxxxx</code></p>
  <p>During testing, the redirects fail in Safari (11) and Firefox (60).
  Safari does not even open a new tab, and when I manually paste the URL in the navbar it gives the following message:</p>
  <blockquote>
  <p>Safari can't open 'whatsapp://chat?code=xxxxxxxxxxxxxxxxxxxxxx'
  because macOS doesn't recognize Internet addresses starting with
  'WhatsApp:'.</p>
  </blockquote>
  <p>On Firefox, the message is:</p>
  <blockquote>
  <p>The address wasn’t understood</p>
  <p>Firefox doesn’t know how to open this address, because one of the
  following protocols (WhatsApp) isn’t associated with any program or is
  not allowed in this context.</p>
  <p>You might need to install other software to open this address.</p>
  </blockquote>
  <p>(note that in both cases the URL is different from the <code>href</code> of the button...)</p>
  <p>Any ideas of what might be causing this and any possible workarounds?</p>