Angular-based screens fail silently

Most if not all of the Angular interfaces require either the "access AJAX API" or "access CiviCRM" permissions. Whenever a user tries to load, for instance, the shopping cart and does not have proper permissions, the page fails to load. Instead of rendering even a generic error message that something has gone wrong, the page is blank, leaving the user wondering what's up.

The use case outlined above, is caused by rejected promises in the API handler that is attempting to fetch supporting data and country list. Angular screens that fetch data prior to rendering should have all reject handlers filled out to display a minimum "We cannot provide this at this time" error if the page will not load and function properly.