fix(api): expose real 500 error stack trace and fix missing func import

inventory-backend/app/services/permission_service.py

@@ -1,6 +1,7 @@
 from app.models.system import SysMenu, SysElement, SysRolePermission
 from app.extensions import db
 from sqlalchemy.exc import SQLAlchemyError
+from sqlalchemy import func
 
 
 class PermissionService: