Unable to migrate from yarn to bun due to critical bun crashes

[Copilot]

Attempted migration from yarn to bun as requested, but encountered systematic bun crashes across all versions tested (1.1.30-1.3.2, canary).

Issue

Bun fails during dependency resolution with segmentation faults:

• Segmentation fault at address 0xB98/0xBC8
• Assertion failure: Expected metadata to be set
• Crashes occur with/without yarn.lock, across all bun versions
• Issue persists even with simplified package.json (no workspaces, no resolutions)

Tested Configurations

• Bun versions: 1.1.30, 1.1.34, 1.1.38, 1.1.42, 1.2.0, 1.3.2, canary
• With/without existing yarn.lock file
• With/without workspace configuration
• Fresh node_modules on each attempt

Root Cause

This appears to be a bun bug with complex monorepo dependency graphs. The rrweb project has:

• 20+ workspace packages with interdependencies
• Custom resolutions for rrweb-cssom (tarball URL)
• Nested workspace structure (packages/, packages/plugins/)

Recommended Alternatives

1. pnpm: More stable alternative to yarn with better monorepo support and performance
2. yarn 4 (Berry): Modern yarn with significant performance improvements over yarn 1.x
3. Wait for bun fix: File upstream bug report and revisit when resolved

No changes committed. Proceeding requires choosing an alternative approach or resolving bun's upstream issues.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• bun.report
  • Triggering command: /usr/bin/curl /usr/bin/curl (dns block)
• edgedl.me.gvt1.com
  • Triggering command: /usr/local/bin/node /usr/local/bin/node install.js (dns block)
• https://storage.googleapis.com/chromium-browser-snapshots/Linux_x64/1036745/chrome-linux.zip
  • Triggering command: /usr/local/bin/node node install.js (http block)
  • Triggering command: /usr/local/bin/node /usr/local/bin/node install.js (http block)
• https://storage.googleapis.com/chromium-browser-snapshots/Linux_x64/869685/chrome-linux.zip
  • Triggering command: /usr/local/bin/node /usr/local/bin/node install.js (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

I want you to try and port the project's package manager from yarn to bun. Make sure you run very comprehensive tests/lint/typechecking/etc. so we don't have to wait for CI to find out if everything works.

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✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[changeset-bot]

⚠️ No Changeset found

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