error handling

app.py

@@ -65,11 +65,13 @@ def respond(
         temperature=temperature,
         top_p=top_p,
     ):
-        token = message.choices[0].delta.content
-
-        if token:
-            response += token
-            yield response
+        if message.choices:
+            token = message.choices[0].delta.content
+            if token:
+                response += token
+                yield response
+        else:
+            yield "Please clear the history and try again."
 
 """
 For information on how to customize the ChatInterface, peruse the gradio docs: https://www.gradio.app/docs/chatinterface