原控制台输出：

node:events:368
      throw er; // Unhandled 'error' event
      ^

Error [ERR_STREAM_WRITE_AFTER_END]: write after end
    at new NodeError (node:internal/errors:371:5)
    at ServerResponse.end (node:_http_outgoing:846:15)
    at Server.<anonymous> (D:\文档\Web视频案例\Node\server\app.js:30:13)
    at Server.emit (node:events:390:28)
    at parserOnIncoming (node:_http_server:951:12)
    at HTTPParser.parserOnHeadersComplete (node:_http_common:128:17)
Emitted 'error' event on ServerResponse instance at:
    at emitErrorNt (node:_http_outgoing:726:9)
    at processTicksAndRejections (node:internal/process/task_queues:84:21) {
  code: 'ERR_STREAM_WRITE_AFTER_END'
}

错误原因：

端口号被占用。

解决办法： 

修改端口号，或者干掉端口号，重新启动项目

干掉端口号方法：

1.进入cmd命令窗口，写netstat -ano|findstr "8080

2.taskkill -PID 13512 -F