Uncaught TypeError: Cannot read properties of undefined (reading '$$')

[damianof]

Describe the bug

When referencing an external component library no longer works.
This used to work i previous version of Svelte.

Now, referencing an external component library throws this error at run time:
"Uncaught TypeError: Cannot read properties of undefined (reading '$$')"

Reproduction

Repro code is here https://github.com/damianof/large-scale-apps-my-svelte-project/tree/debug-%24%24-issue
Steps:

• npm install and build ./my-component-library
• npm install ./my-svelte-project
• run my-svelte-project with npm start

Logs

No response

System Info

System:
    OS: macOS 12.6
    CPU: (8) arm64 Apple M2
    Memory: 253.02 MB / 8.00 GB
    Shell: 5.8.1 - /bin/zsh
  Binaries:
    Node: 16.17.0 - /usr/local/bin/node
    npm: 8.19.2 - /usr/local/bin/npm
  Browsers:
    Chrome: 106.0.5249.119
    Safari: 16.0

Severity

blocking all usage of svelte

[Prinzhorn]

I didn't run your project but from looking at it, here's what I think: Your component library does not specify a svelte entry point in package.json. So your project is importing the compiled components and now at runtime you have two Svelte instances (with potentially different versions). Refs #3165

Examples:

https://github.com/sveltejs/svelte-scroller/blob/b50ec28bb7fdd9dc8b08ec59b8a34ea7b1d684e6/package.json#L5
https://github.com/isaacHagoel/svelte-dnd-action/blob/148ee38b63919074637095aecfd6e3dcf6770772/package.json#L3
https://grep.app/search?current=2&q=%22svelte%22%3A%20%22.&filter[path.pattern][0]=package.json

[Prinzhorn]

Yeah, this perfectly explains it given your comment here https://github.com/damianof/large-scale-apps-my-svelte-project/blob/b078d3328024ee34d7322a427eddbb218e447923/my-svelte-project/src/App.svelte#L2-L3
Because when you import from 'my-component-library' it's the compiled components.

[simo-an]

If I compile svelte component to web components.

How can I use this web component at my svelte project ?

[dummdidumm]

Closing as outdated, Svelte 5 uses a different runtime. Also this sounds like using a compiled version of a Svelte component declaratively (i.e. <Component >/ and not new Component(..) / mount(Component)) within a Svelte app with a different version of the runtime, which generally isn't supported.