fix annotation query exception (#1771)

Co-authored-by: jyong <jyong@dify.ai>

api/core/completion.py

@@ -341,6 +341,7 @@ class Completion:
         app = conversation_message_task.app
         annotation_reply = app_model_config.annotation_reply_dict
         if annotation_reply['enabled']:
+            try:
                 score_threshold = annotation_reply.get('score_threshold', 1)
                 embedding_provider_name = annotation_reply['embedding_model']['embedding_provider_name']
                 embedding_model_name = annotation_reply['embedding_model']['embedding_model_name']
@@ -401,6 +402,9 @@ class Completion:
                                                                     from_source,
                                                                     score)
                         return True
+            except Exception as e:
+                logging.warning(f'Query annotation failed, exception: {str(e)}.')
+                return False
         return False
 
     @classmethod