FHIR CustomBuiltinOperations - handling error 500 in production

Hi,

I've overrided the HS.FHIRServer.Storage.BuiltInOperations class, and generally all works fine except of error handling. Where can I find a server setting option to ask IRIS to return OperationOutcome if an Internal Server Error occurs? Currently it returns non-informative HTML instead of JSON/OperationOutcome.