Fix uninitialised values (SF #1354920 and #1498999)

docs/Changelog

@@ -31,6 +31,7 @@ pisg (0.69) - ??
        in the CSS file.
      + Fix title tooltip (SF #1492153).
      + Fix -cchannels option (SF #1369457).
+     + Fix uninitialised values in charts (SF #1354920 and #1498999)
    * Features:
      + Add "+CVS" to versionstring if ./CVS is found
    * Parsers:

modules/Pisg/Parser/Logfile.pm

@@ -588,6 +588,7 @@ sub _parse_file
     my $wordcount = sqrt(sqrt(keys %{$stats->{wordcounts}})); # remove less frequent words
     foreach my $word (keys %{$stats->{wordcounts}}) {
         if ($stats->{wordcounts}->{$word} < $wordcount) {
+            next if defined $stats->{chartcounts}{$word};
             delete $stats->{wordcounts}->{$word};
             delete $stats->{wordnicks}->{$word};
             delete $stats->{word_upcase}->{$word};