if($@) {
  # assign an empty (but defined) string to $bus_url
  $bus_url = '';
}
else {
  # assign tag contents to $bus_url
  $bus_url = $BusUrl->item(0)->getChildAtIndex(0)->getData(); 
}
##</code><code>##

my $BusUrl = $contact->getElementsByTagName( "BusinessUrl" );

# check if tag is defined and has children
if (defined $BusUrl && $BusUrl->hasChildNodes) {
  $bus_url = $BusUrl->item( 0 )->getChildAtIndex( 0 )->getData();
}
# otherwise assign an empty string
else {
  $bus_url = '';
}