main: Error out on D-Bus communication errors
The bug reporting tool in Fedora, in its infinite wisdom, considers innocuous exceptions that occur when system daemons aren't running to be bug report worthy.
Catch all the D-Bus communication errors, print an error message detailing the problem and exit with a return value of 1 when they occur instead of printing an exception.
See:
https://bugzilla.redhat.com/show_bug.cgi?id=2019536