We have hundreds of projects that run on Bun. (Some are Bun-specific for whatever reason, but most are "runtime-agnostic TypeScript code that runs on Bun, Node 24.2+, and Deno, but that means they run their test suites on Bun, in addition to the other two.)

Out of curiosity, I installed the canary Bun and just ran a bunch of them. It didn't take me long to find one that works on stable Bun and crashes on "canary" Bun.

      schematic git:(main)  bun upgrade --canary
    [1.55s] Upgraded.
    
    Welcome to Bun's latest canary build!
    
    Report any bugs:
    
        https://github.com/oven-sh/bun/issues
    
    Changelog:
    
        https://github.com/oven-sh/bun/compare/0d9b296af...19d8ade2c
    
      schematic git:(main)  bun run main.ts serve
    Schematic Editor running at http://localhost:4200
    Bundled page in 25ms: src/web/index.html
    frontend TypeError: Cannot destructure property 'isLikelyComponentType' from null or undefined value
        at V0 (http://localhost:4200/_bun/client/index-00000000ac7e3555.js:24:2534)
        at reactRefreshAccept (http://localhost:4200/_bun/client/index-00000000ac7e3555.js:21:6090)
        at http://localhost:4200/_bun/client/index-00000000ac7e3555.js:8766:27
        at CY (http://localhost:4200/_bun/client/index-00000000ac7e3555.js:21:8973)
        at nY (http://localhost:4200/_bun/client/index-00000000ac7e3555.js:21:9285)
        (...more like this...)
        at m (http://localhost:4200/_bun/client/index-00000000ac7e3555.js:21:8773)
        at http://localhost:4200/_bun/client/index-00000000ac7e3555.js:24:6482
        at http://localhost:4200/_bun/client/index-00000000ac7e3555.js:24:6548
        from browser tab http://localhost:4200/
    ^C
      schematic git:(main)  bun upgrade --stable
    Downgrading from Bun 1.3.14-canary to Bun v1.3.14
    [2.02s] Upgraded.
    
    Welcome to Bun v1.3.14!
    
    What's new in Bun v1.3.14:
    
        https://bun.com/blog/release-notes/bun-v1.3.14
    
    Report any bugs:
    
        https://github.com/oven-sh/bun/issues
    
    Commit log:
    
        https://github.com/oven-sh/bun/compare/bun-v1.3.14...bun-v1.3.14
      schematic git:(main)  bun run main.ts serve
    Schematic Editor running at http://localhost:4200
    [browser] Version mismatch, hard-reloading
    Bundled page in 20ms: src/web/index.html
    
    # working fine as usual... ¯\_(ಠ_ಠ)_/¯

I mean "passes test suite" is one thing. And a good thing. But... "doesn't break any (or even, say 99.5%) of the apps deployed around the world that are built on bun" is a pretty radically different thing.

It's hard to feel like this is responsible behavior, but I will reserve judgement for now, and see how long they persist this "canary" phase.

If they extend it for a lengthy period, and even like, fix bugs on the Zig version and the Rust "canary" version, then... I would be mollified to a great extent, since it is so easy to switch between the Zig stable version and the Rust canary version.

As a pretty heavy user of Bun, I'm actually pretty psyched for it to switch to Rust... but given the abruptness and speed so far, I can't quite shake the "new AI dealer getting high on his own supply" vibe.

But I hope they enter an intensive phase of prioritizing any and all "canary" bugs, and come out on the other side with a better product, and an even faster rate of improvement (which has honestly been pretty wild already).

(Yes, of course, I will have my clanker file a bug report with repro... but that may take a few days.)