update

app/core/runner/llm_callback_handler.py

@@ -66,7 +66,7 @@ class LLMCallbackHandler:
                             message.tool_calls, tool_call_delta
                         )
 
-                elif delta.content:
+                elif delta.content is not None:
                     # call on delta message received
                     if not self.final_message_started:
                         self.final_message_started = True