use strict;
use warnings;

my $string = 'Return code is';
my $filename = 'trace.Discovery';
my %errors =();
my $total = 0;

if (open(my $fh, '<:encoding(UTF-8)', $filename)) {
  while (my $row = <$fh>) {
    chomp $row;
    if ($row =~ /\Q$string\E/) {
      my $digit =  (split /\:/, $row)[-1];
      $errors{$digit}++;
      }
  }
} else {
  print "Could not open file '$filename'\n";
  warn "This is the error --> $!";
}

# First attempt to print keys
foreach ( sort keys %errors ) {
        print "$_ - $errors{$_}\n";
        $total = $total + $errors{$_};
}
        print "Total errors --> $total\n";

### Another attempt to print the keys.
while( my( $key, $value ) = each %errors ){
    print "$key: $value\n";
}