fix: generate_more_like_this function issue (#722)

api/core/completion.py

@@ -388,7 +388,6 @@ And answer according to the language of the user's question.
             pre_prompt=pre_prompt,
             query=message.query,
             inputs=message.inputs,
-            chain_output=None,
             agent_execute_result=None,
             memory=None
         )