Wrap main functions to handle uncaught exceptions

Coverity reports multiple instances where formatting facilities can
throw (e.g. invalid format string).

A wrapper to handle formatting exceptions is added in a follow-up
change, but it is a good practice to catch exceptions at the top level
nonetheless.

Reported-by: Coverity Scan
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ie55af338b9ef1f7d6e8825055cfc2e7037cdd80e