title: Open link in custom app only if protocol handler is registered, otherwise open in browser
body: <p>My app sends email notifications on certain activity events. I wish to add link to those emails that will open my custom electron app that has registered protocol (myapp://) if that app exists on user's computer.</p>
  
  <p>If that is not installed on email recipient's computer or protocol is not handled link should open in browser.</p>
  
  <p>I suspect this is not possible, but i really hope i overlooked some great way to do that.</p>
  
  <p>Workarounds are welcome.</p>