René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Inconsistent behavior of nextTick and queueMicrotask","articleBody":"Consider this snippet:\r\n\r\n```js\r\nconst { EventEmitter } = require('node:events')\r\n\r\nfunction run (name) {\r\n  return new Promise((resolve) => {\r\n    const e = new EventEmitter()\r\n    process.nextTick(() => {\r\n      e.emit('error', new Error())\r\n    });\r\n    resolve(e)\r\n  }).then(((e) => {\r\n    e.on('error', err => {\r\n      console.error(`### ${name} ###`, err)\r\n    })\r\n  }))\r\n}\r\n\r\nqueueMicrotask(run.bind(null, 'queueMicrotask'))\r\nsetImmediate(run.bind(null, 'setImmediate'))\r\n```\r\n\r\nThis results in\r\n\r\n```\r\n### queueMicrotask ### Error\r\n    at /Users/matteo/c.cjs:7:23\r\n    at process.processTicksAndRejections (node:internal/process/task_queues:77:11)\r\nnode:events:492\r\n      throw er; // Unhandled 'error' event\r\n      ^\r\n\r\nError\r\n    at /Users/matteo/c.cjs:7:23\r\n    at process.processTicksAndRejections (node:internal/process/task_queues:77:11)\r\nEmitted 'error' event at:\r\n    at /Users/matteo/c.cjs:7:9\r\n    at process.processTicksAndRejections (node:internal/process/task_queues:77:11)\r\n\r\nNode.js v20.10.0\r\n```\r\n\r\nWhy is this an issue? In most part of Node.js core,\r\nwe use `process.nextTick(() => ee.emit('error'))` to let users install event handlers.\r\nHowever, if an `EventEmitter` is returned by an `async function`, there is a significant possibility that the error could not be caught.\r\n\r\n(This is essentially a problem for Node.js streams). ","author":{"url":"https://github.com/mcollina","@type":"Person","name":"mcollina"},"datePublished":"2023-12-14T14:11:48Z","url":"https://github.com/nodejs/node/issues/51156"}