Upgrade from 2.22.5 to 2.23.0 breaks with "Cannot read properties of undefined (reading 'data')"

[RikuVan]

Describe the bug

I after noticing some javascript features where breaking in the production deployment. I rolled back everthing and started upgrading packages one by one until I saw that 2.22.5 -> 2.23.0 introduced this change. I get:

TypeError: Cannot read properties of undefined (reading 'data')

Other deps include:

"@sveltejs/vite-plugin-svelte": "^6.1.1",
  "svelte": "^5.38.0",
  "vite": "^7.1.1",

I would really appreciate a tip about what changed as I have not been able to track down the issue. It is a private repo but I can give temp access to a maintainer if this helps.

Reproduction

Please request access to this PR which also has a vercel deployment: https://github.com/RikuVan/danceup.fi/pull/165

System Info

System:
    OS: macOS 15.6
    CPU: (8) arm64 Apple M3
    Memory: 156.63 MB / 24.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 24.4.0 - ~/.nvm/versions/node/v24.4.0/bin/node
    npm: 11.4.2 - ~/.nvm/versions/node/v24.4.0/bin/npm
  Browsers:
    Chrome: 139.0.7258.66
    Safari: 18.6
  npmPackages:
    @sveltejs/adapter-node: ^5.2.14 => 5.2.14 
    @sveltejs/adapter-vercel: ^5.8.2 => 5.8.2 
    @sveltejs/enhanced-img: ^0.7.1 => 0.7.1 
    @sveltejs/kit: ^2.23.0 => 2.27.3 
    @sveltejs/vite-plugin-svelte: ^6.1.1 => 6.1.1 
    svelte: ^5.38.0 => 5.38.0 
    vite: ^7.1.1 => 7.1.1

Severity

blocking an upgrade

Additional Information

No response

[RikuVan]

I also tried downgrading vite to 6.3.5 but it did not help.

[RikuVan]

Also this does not show in development or when building and testing with the "preview" command.

[lubiah]

I'm also facing this error

[stayradiated]

I noticed a similar error when using storybook to render my components with @sveltejs/kit 2.27.2.

can't access property "data", __SVELTEKIT_PAYLOAD__ is undefined

Rolling back to @sveltejs/kit 2.27.1 works for me.

[ThomasBoom89]

Probably a duplicate of #14143