You may wish to consider using an internal die.

sub _die {
   my $err_no = shift;
   my @msg = @_;
   
   print STDERR join "\n",@msg;
   exit $err_no;
}
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Alternatively, replace exit $err_no; with ($! = $err_no) && (die());.

Then call _die($err_num, "This thing is dead.") when you want the alternate behavior.