Why does AlphaCommerceHub use a non-standard «Internal Processing Error please resend the request» `ResponseMessage` value for the «1059» `ResponseCode` despite the documented message for this code is «PaymentID is required»?

An example with such undocumented ResponseCode / ResponseMessage pair: Why does AlphaCommerceHub respond 1059 / «Internal Processing Error please resend the request» to a PayPal’s PaymentStatus API request?

The ResponseCode / ResponseMessage pairs are documented in the «API Integration Guide(Nov 2017)» → «Response Codes» table.

I have got a response from AlphaCommerceHub:

RG: This inconsistency has been resolved. There was some legacy error handling that captured using a different response message for 1059