if _, err = xioutil.Copy(httpWriter, gr); err != nil {
		if !httpWriter.HasWritten() && !statusCodeWritten {
			// write error response only if no data or headers has been written to client yet
			writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
			return
		}
		return
	}

	if err = httpWriter.Close(); err != nil {