ServiceStack.HttpResponseExtensionsInternal.WriteErrorToResponse C# (CSharp) Method

        public static Task WriteErrorToResponse(this IResponse httpRes, IRequest httpReq,
            string contentType, string operationName, string errorMessage, Exception ex, int statusCode)
        {
            if (ex == null)
                ex = new Exception(errorMessage);

            var errorDto = ex.ToErrorResponse();
            HostContext.AppHost.OnExceptionTypeFilter(ex, errorDto.ResponseStatus);

            if (HandleCustomErrorHandler(httpRes, httpReq, contentType, statusCode, errorDto))
                return TypeConstants.EmptyTask;

            if ((httpRes.ContentType == null || httpRes.ContentType == MimeTypes.Html) 
                && contentType != null && contentType != httpRes.ContentType)
            {
                httpRes.ContentType = contentType;
            }
            if (HostContext.Config.AppendUtf8CharsetOnContentTypes.Contains(contentType))
            {
                httpRes.ContentType += ContentFormat.Utf8Suffix;
            }

            var hold = httpRes.StatusDescription;
            var hasDefaultStatusDescription = hold == null || hold == "OK";

            httpRes.StatusCode = statusCode;

            httpRes.StatusDescription = hasDefaultStatusDescription
                ? (errorMessage ?? HttpStatus.GetStatusDescription(statusCode))
                : hold;

            httpRes.ApplyGlobalResponseHeaders();

            var serializer = HostContext.ContentTypes.GetResponseSerializer(contentType);
            serializer?.Invoke(httpReq, errorDto, httpRes);

            httpRes.EndHttpHandlerRequest(skipHeaders: true);

            return TypeConstants.EmptyTask;
        }