Update chain_app.py

chain_app.py

@@ -2342,10 +2342,10 @@ async def main(message: cl.Message):
           stream=True
         )
         for chunk in completion:
-          await msg.stream_token(chunk.choices[0].delta.content)
+            if chunk.choices[0].delta.content is not None:
+              await msg.stream_token(chunk.choices[0].delta.content)
         
 
-
     elif chat_profile == 'Llama-3.1-70B':
         completion = groq_client.chat.completions.create(
             model="llama-3.1-70b-versatile",