title: how to handle routes that don't match a pattern
body: <p>Is there a way to specify a route handler that handles all routes that do not match the routes defined?  Like a catch-all route or a default route handler.</p>
  
  <p>I'm running into the use case where I want a default page to load if no matching routes are found. For example, it would load a "page not found" page.</p>