Patch a bug in obitag when some reference sequences have taxid absent from the taxonomy

pkg/obitax/taxon.go

@@ -27,7 +27,7 @@ type Taxon struct {
 // Returns:
 //   - A formatted string representing the Taxon in the form "taxonomy_code:taxon_id [scientific_name]".
 func (taxon *Taxon) String() string {
-	if taxon == nil {
+	if taxon == nil || taxon.Node == nil {
 		return "NA"
 	}
 	return taxon.Node.String(taxon.Taxonomy.code)

pkg/obitax/taxonslice.go

@@ -145,3 +145,18 @@ func (slice *TaxonSlice) Set(index int, taxon *Taxon) *TaxonSlice {
 
 	return slice
 }
+
+func (slice *TaxonSlice) Push(taxon *Taxon) *TaxonSlice {
+	if slice.taxonomy != taxon.Taxonomy {
+		log.Panic("Cannot add taxon from a different taxonomy")
+	}
+
+	slice.slice = append(slice.slice, taxon.Node)
+
+	return slice
+}
+
+func (slice *TaxonSlice) ReduceToSize(size int) *TaxonSlice {
+	slice.slice = slice.slice[:size]
+	return slice
+}