Update termSearch.ts

Return empty array rather than null

src/routes/termSearch.ts

@@ -21,7 +21,7 @@ const mapMatchingTextSearchResults: MapToTermSearchResponseFunction = (
         const row = matchingText.find((row) =>
           row.parallelId === parallelId && row.moduleId === moduleId
         );
-        return row ? mapTextResult(row) : null;
+        return row ? mapTextResult(row) : [];
       })
     )
   );