fix：修复表达方式空构建问题

src/chat/focus_chat/expressors/exprssion_learner.py

@@ -204,7 +204,8 @@ class ExpressionLearner:
         random_msg: Optional[List[Dict[str, Any]]] = get_raw_msg_by_timestamp_random(
             current_time - 3600 * 24, current_time, limit=num
         )
-        if not random_msg:
+        # print(random_msg)
+        if not random_msg or random_msg == []:
             return None
         # 转化成str
         chat_id: str = random_msg[0]["chat_id"]
@@ -216,7 +217,7 @@ class ExpressionLearner:
             chat_str=random_msg_str,
         )
 
-        # logger.info(f"学习{type_str}的prompt: {prompt}")
+        logger.info(f"学习{type_str}的prompt: {prompt}")
 
         try:
             response, _ = await self.express_learn_model.generate_response_async(prompt)