local $SIG{__DIE__} = sub {
  my ($d) = ( $_[0] =~ /line (\d+)\.$/ );
  unless ($d) {
    print STDERR $_[0];
    return;
  }
  
  my $context = 3; #number of context lines
  
  seek DATA,0,0;
  while(<DATA>) {
    next if $. < ($d-$context);  #cycle until context starts
    
    warn ($. == $d ? '>' : ' ')  #mark line if it contains the error
         .sprintf('%4d ',$.)     #use 4-place line numbers (alignment)
         .$_;                    #show code on line
         
    last if $. > ($d+$context);  #move on once we've finished context
  }
};