Svelte 5: `next.173` broke <something>

[huntabyte]

Describe the bug

I am currently trying to nail down what specifically this update broke (quite complex reproduction atm) and will update this issue with more details, but putting it out here in case it's immediately obvious to someone.

What's most confusing to me is that I'm not using any stores, and it appears that only stores were impacted by #12277.

Was informed about non-changeset changes that were also rolled up into next.173, specifically #12272

Here's behavior on next-172:

CleanShot.2024-07-07.at.16.22.26.mp4

and here's behavior on next-173.:

CleanShot.2024-07-07.at.16.21.32.mp4

Reproduction

Working on taking this more complex example and creating a minimal reproduction.

Logs

No response

System Info

System:
    OS: macOS 14.4.1
    CPU: (12) arm64 Apple M2 Max
    Memory: 639.52 MB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 18.18.2 - ~/.nvm/versions/node/v18.18.2/bin/node
    npm: 9.8.1 - ~/.nvm/versions/node/v18.18.2/bin/npm
    pnpm: 8.15.8 - ~/Library/pnpm/pnpm
    bun: 1.0.25 - ~/.bun/bin/bun
  Browsers:
    Edge: 126.0.2592.87
    Safari: 17.4.1
  npmPackages:
    svelte: 5.0.0-next.173 => 5.0.0-next.173

Severity

blocking an upgrade

[paoloricciuti]

@huntabyte can you still share the code? I might try to come up with a minimal reproduction anyway

[paoloricciuti]

Btw despite the changelog there were actually more changes from 172 to 173

svelte@5.0.0-next.172...svelte@5.0.0-next.173

So #12272 could actually be the culprit here (and it seems more likely if you don't use stores)

[huntabyte]

Ahh, that would make a lot more sense (that there are more changes) @paoloricciuti:

Here's the branch running on the latest version of Svelte (same behavior from 173+): huntabyte/bits-ui#469 (Navigation Menu component)

From my debugging so far it seems to not be registering mount / destroy properly in the Mounted component used here which is causing it to get stuck in a broken state:
packages/bits-ui/src/lib/bits/navigation-menu/components/navigation-menu-content.svelte

[huntabyte]

Yeah the more I look at #12272 the more familiar the code changes look to similar bugs I've run into in the past that I believe @trueadm was able to sort out regarding unowned state

[tobiasBora]

In one application of mine, I get an error The this={...}property of asvelte:component must be a Svelte component, if defined, but I can't find exactly what caused this and I don't have much time to investigate more, but if it helps this might be related as this error is gone in 172…