test(db): cover zero-label term and duplicate vocabulary key; use try_get in vocabulary_by_key

crates/db/src/vocab.rs

@@ -39,10 +39,7 @@ where
         .fetch_optional(executor)
         .await?;
 
-    Ok(row.map(|r| Vocabulary {
-        id: VocabularyId::from_uuid(r.get("id")),
-        key: r.get("key"),
-    }))
+    row.map(map_vocabulary).transpose()
 }
 
 /// Insert a term and its labels. Multiple statements — pass a transaction
@@ -129,6 +126,13 @@ where
     Ok(found.map(|_| TermRef::new(term_id, vocabulary_id)))
 }
 
+fn map_vocabulary(row: sqlx::postgres::PgRow) -> Result<Vocabulary, sqlx::Error> {
+    Ok(Vocabulary {
+        id: VocabularyId::from_uuid(row.try_get("id")?),
+        key: row.try_get("key")?,
+    })
+}
+
 fn map_term(row: sqlx::postgres::PgRow) -> Result<Term, sqlx::Error> {
     let labels: sqlx::types::Json<Vec<LocalizedLabel>> = row.try_get("labels")?;