message: fix: don't emit empty aa ranges
diff: @@ -119,15 +119,15 @@ impl GeneAaRange {
  /// Finds contiguous ranges (segments) consisting of a given amino acid in the sequence.
  pub fn find_aa_letter_ranges(translations: &[Result<Translation, Report>], letter: Aa) -> Vec<GeneAaRange> {
  keep_ok(translations)
  - .map(|Translation { gene_name, seq, .. }| {
  + .filter_map(|Translation { gene_name, seq, .. }| {
  let ranges = find_letter_ranges_by(seq, |candidate| candidate == letter);
  let length = ranges.iter().map(LetterRange::len).sum();
  - GeneAaRange {
  + (length > 0).then(|| GeneAaRange {
  gene_name: gene_name.clone(),
  letter,
  ranges,
  length,
  - }
  + })
  })
  .collect()
  }
  