create two separate highlights

app.py

@@ -40,9 +40,11 @@ def ner(text):
         if result.get("entity_group"):
             result["entity"] = "Knowledge"
             del result["entity_group"]
-    
-    output_skills = aggregate_span(output_skills)
-    output_knowledge = aggregate_span(output_knowledge)
+
+    if len(output_skills) > 0:
+        output_skills = aggregate_span(output_skills)
+    if len(output_knowledge) > 0:
+        output_knowledge = aggregate_span(output_knowledge)
 
     return {"text": text, "entities": output_skills}, {"text": text, "entities": output_knowledge}