Ensure exceptions / failures are visible to site admins
Example use case: including <style>.foo { color: red }</style>
in a CiviCRM mailing template can cause the scheduled reminders action to fail with a fatal error (#58 (closed), PR#15436 on Github).
If #1256 (closed) is implemented then Smarty should throw an exception instead. Once that's the case, CiviCRM can trap the exceptions and record them in some central log (akin to Drupal dblog), and from there we can show a status notification to site admins which informs them of the fact that some component may not be functioning as expected.
This is useful because it closes the loop from problems like "anonymous user could not complete contribution" or "users are no longer getting membership reminders after theme updates" and some actionable response which starts with "site admin knows there's a problem".
I don't see this on existing issue lists, but please point me in the right direction if there is such a thing.
We don't need #1256 (closed) resolved to add this improvement.