It seems that the historical series requests in RKD do not return any error codes in response and every error condition should be handled as an exception: FaultException, CommunicationException etc,
Looking into the exception's FaultReason produces the text like ''Backend error: 'NOT_AUTHORIZED'".
Is there an exhaustive list of "reasons" or at least the set of fault categories that can be matched in the FaultReason.text or Exception.Message for the lack of a better alternative?