Fix summary default in opera log middleware (#809)

Author: wu-clan

backend/middleware/opera_log_middleware.py

@@ -74,7 +74,7 @@ async def dispatch(self, request: Request, call_next: Any) -> Response:
 
             # 此信息只能在请求后获取
             _route = request.scope.get('route')
-            summary = getattr(_route, 'summary', '')
+            summary = getattr(_route, 'summary') or ''
 
             try:
                 # 此信息来源于 JWT 认证中间件