if $q is the cgi object; you might try this (pseudo halfway code)

# try to open or die but not immediately
open $file or go_away($file,$!);

sub go_away
{
$file = shift;
$error = shift;
# tell the surfer something nice
print $q->redirect($url_to_see_nicer_pages_than_500error);

# now die and preserve my error log from being incomplete
die(couldn't open $file: $error);
}
[download]

so U don't loose the info to track on errors and can use your __DIE__ handler but fake a "nice world" to the surfer

Have a nice day
All decision is left to your taste