Update src/txagent/txagent.py

src/txagent/txagent.py

@@ -241,8 +241,10 @@ class TxAgent:
                                 full_message, temperature=temperature,
                                 max_new_tokens=1024, max_token=99999,
                                 call_agent=False, call_agent_level=call_agent_level)
-                            call_result = call_result.split(
-                                '[FinalAnswer]')[-1].strip()
+                            if call_result is None:
+                                call_result = "⚠️ No content returned from sub-agent."
+                            else:
+                                call_result = call_result.split('[FinalAnswer]')[-1].strip()
                         else:
                             call_result = "Error: The CallAgent has been disabled. Please proceed with your reasoning process to solve this question."
                     else: