Better message in lookup failure

app.py

@@ -72,8 +72,10 @@ if __name__ == "__main__":
         )
 
         context = f"Looking at the video titled {best_chunk.title}"
+        answer = completion.choices[0].message.content
+        answer = answer if "<|UNKNOWN|>" not in answer else "Couldn't find the answer."
 
-        return completion.choices[0].message.content, context
+        return answer, context
 
     def get_answer_better(api_key: str, query: str) -> str:
         client = OpenAI(api_key=api_key)