René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Cannot read properties of undefined when requiring `node:fs` with hooks","articleBody":"### Version\n\nv22.20.0, v23.11.1, v24.8.0\n\n### Platform\n\n```text\nLinux exports-undefined 6.8.0-84-generic #84-Ubuntu SMP PREEMPT_DYNAMIC Fri Sep  5 22:36:38 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux\n```\n\n### Subsystem\n\nmodule\n\n### What steps will reproduce the bug?\n\n`register.mjs`:\n```\nimport { registerHooks } from 'node:module';\nimport { fileURLToPath } from 'node:url';\nimport { dirname, join } from 'node:path';\n\nfunction resolve(specifier, context, nextResolve) {\n\tconst path = fileURLToPath(import.meta.url);\n\tconst dir = dirname(path);\n\tswitch (specifier) {\n\t\tcase 'fs':\n\t\tcase 'node:fs':\n\t\t\tspecifier = join(dir, 'fs-mock.mjs');\t\t\t\t\t\n\t}\n\n\treturn nextResolve(specifier, context);\n};\n\nregisterHooks({ resolve });\n```\n`fs-mock.mjs`:\n```\nexport const constants = {\n\tF_OK: 42\n}\n```\n`index.cjs`:\n```\nconst fs = require('node:fs');\nconsole.log(fs.constants.F_OK);\n```\nRun `node --import=./register.mjs index.cjs`.\n\n### How often does it reproduce? Is there a required condition?\n\nHappens reliably when `fs` is being required as `node:fs`, does not happen when required as `fs`, or when imported.\n\n### What is the expected behavior? Why is that the expected behavior?\n\nShould either require `fs-mock.mjs`, or require original (builtin) `fs` module.\n\n### What do you see instead?\n\n```\nnode:internal/modules/cjs/loader:1155\n  return mod.exports;\n             ^\n\nTypeError: Cannot read properties of undefined (reading 'exports')\n    at loadBuiltinWithHooks (node:internal/modules/cjs/loader:1155:14)\n    at Function._load (node:internal/modules/cjs/loader:1197:20)\n    at TracingChannel.traceSync (node:diagnostics_channel:322:14)\n    at wrapModuleLoad (node:internal/modules/cjs/loader:237:24)\n    at Module.require (node:internal/modules/cjs/loader:1463:12)\n    at require (node:internal/modules/helpers:147:16)\n    at Object.\u003canonymous\u003e (/vagrant/index.cjs:1:12)\n    at Module._compile (node:internal/modules/cjs/loader:1706:14)\n    at Object..js (node:internal/modules/cjs/loader:1839:10)\n    at Module.load (node:internal/modules/cjs/loader:1441:32)\n```\n\n### Additional information\n\nOutput from `NODE_DEBUG=* node --import=./register.mjs index.cjs`:\n[log.txt](https://github.com/user-attachments/files/22530678/log.txt)","author":{"url":"https://github.com/BadIdeaException","@type":"Person","name":"BadIdeaException"},"datePublished":"2025-09-25T07:08:28.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":9},"url":"https://github.com/60005/node/issues/60005"}