Chainlit#1178 Fix AttributeError: 'ChatCompletionChunk' object has no…

… attribute 'get' (Chainlit#1229)

backend/chainlit/llama_index/callbacks.py

@@ -154,7 +154,7 @@ def on_event_end(
 
             token_count = self.total_llm_token_count or None
             raw_response = response.raw if response else None
-            model = raw_response.get("model", None) if raw_response else None
+            model = getattr(raw_response, "model", None)
 
             if messages and isinstance(response, ChatResponse):
                 msg: ChatMessage = response.message