fix bug in api (#1088)

### What problem does this PR solve?

#1075 

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

api/apps/api_app.py

             try:
                 for ans in chat(dia, msg, True, **req):
                     fillin_conv(ans)
-                    rename_field(rename_field)
+                    rename_field(ans)
                     yield "data:" + json.dumps({"retcode": 0, "retmsg": "", "data": ans}, ensure_ascii=False) + "\n\n"
                 API4ConversationService.append_message(conv.id, conv.to_dict())
             except Exception as e:

rag/llm/embedding_model.py

                 token_count += resp["usage"]["total_tokens"]
             return np.array(res), token_count
         except Exception as e:
-            raise Exception("Account abnormal. Please ensure it's on good standing.")
+            raise Exception("Account abnormal. Please ensure it's on good standing to use QWen's "+self.model_name)
         return np.array([]), 0
 
     def encode_queries(self, text):
             return np.array(resp["output"]["embeddings"][0]
                             ["embedding"]), resp["usage"]["total_tokens"]
         except Exception as e:
-            raise Exception("Account abnormal. Please ensure it's on good standing.")
+            raise Exception("Account abnormal. Please ensure it's on good standing to use QWen's "+self.model_name)
         return np.array([]), 0