function WritableStreamFinishInFlightWriteWithError(stream, error) {
		        stream._inFlightWriteRequest._reject(error);
		        stream._inFlightWriteRequest = undefined;
		        WritableStreamDealWithRejection(stream, error);
		    }
Node-fetch non-spec method
returning all headers and their values as array
@returns {Record<string, string[]>}