Function cancel

js/worker.js:253–263

(reason)

            // https://streams.spec.whatwg.org/#example-rs-push-backpressure
        },
        cancel(reason) {
            // 1. pipe WritableStream has error, this cancel will called, so ws handle server close into here
            // 2. if readableStream is cancel, all controller.close/enqueue need skip,
            // 3. but from testing controller.error still work even if readableStream is cancel
            if (readableStreamCancel) {
                return;
            }
            log(`ReadableStream was canceled, due to ${reason}`)
            readableStreamCancel = true;
            safeCloseWebSocket(webSocketServer);
        }
    });

    return stream;