[Koha] Delete patron via REST API - Missing property - Status 500

Hello, I want to delete patrons with the REST API. If the patron has no checkouts, everything works fine. But when the patron has checkouts, I get this as response from my HTTP DELETE request: {"errors":[{"message":"Missing property.","path":"\/errors"}],"status":500} The API docs say that it should return a 409 status with errors → has_checkouts https://api.koha-community.org/#operation/deletePatron Any ideas? I send the requests to this url: https://our-library-intra.com/api/v1/patrons/23 Regards, Stephan