False `custom_element_props_identifier` errors with no custom elements

[kyoshino]

Describe the bug

After sveltejs/svelte#16003 landed in svelte@5.33.4, I started getting custom_element_props_identifier errors with a rest prop even though my project doesn’t use custom elements. These errors come from ESLint with eslint-plugin-svelte installed, but not from svelte-check.

I could silence the errors by adding svelte/valid-compile: off to the ESLint config, but something is going wrong on the Svelte side. It may be a bug in eslint-plugin-svelte, but I’m not sure.

Reproduction

Repo: https://github.com/sveltia/sveltia-cms

One of the errors is raised here: image.svelte

A minimum reproduction:

<script>
  let { ...rest } = $props();
</script>

Logs

$ eslint .

/Users/Kohei/Sites/sveltia-cms/src/lib/components/assets/shared/asset-preview.svelte
  45:5  error  Using a rest element or a non-destructured declaration with `$props()` means that Svelte can't infer what properties to expose when creating a custom element. Consider destructuring all the props or explicitly specifying the `customElement.props` option.
https://svelte.dev/e/custom_element_props_identifier(custom_element_props_identifier)  svelte/valid-compile

/Users/Kohei/Sites/sveltia-cms/src/lib/components/assets/shared/image.svelte
  33:5  error  Using a rest element or a non-destructured declaration with `$props()` means that Svelte can't infer what properties to expose when creating a custom element. Consider destructuring all the props or explicitly specifying the `customElement.props` option.
https://svelte.dev/e/custom_element_props_identifier(custom_element_props_identifier)  svelte/valid-compile

/Users/Kohei/Sites/sveltia-cms/src/lib/components/assets/shared/video.svelte
  30:5  error  Using a rest element or a non-destructured declaration with `$props()` means that Svelte can't infer what properties to expose when creating a custom element. Consider destructuring all the props or explicitly specifying the `customElement.props` option.
https://svelte.dev/e/custom_element_props_identifier(custom_element_props_identifier)  svelte/valid-compile

/Users/Kohei/Sites/sveltia-cms/src/lib/components/common/list-container.svelte
  18:5  error  Using a rest element or a non-destructured declaration with `$props()` means that Svelte can't infer what properties to expose when creating a custom element. Consider destructuring all the props or explicitly specifying the `customElement.props` option.
https://svelte.dev/e/custom_element_props_identifier(custom_element_props_identifier)  svelte/valid-compile

/Users/Kohei/Sites/sveltia-cms/src/lib/components/common/listing-grid.svelte
  25:5  error  Using a rest element or a non-destructured declaration with `$props()` means that Svelte can't infer what properties to expose when creating a custom element. Consider destructuring all the props or explicitly specifying the `customElement.props` option.
https://svelte.dev/e/custom_element_props_identifier(custom_element_props_identifier)  svelte/valid-compile

/Users/Kohei/Sites/sveltia-cms/src/lib/components/common/page-container-main-area.svelte
  21:5  error  Using a rest element or a non-destructured declaration with `$props()` means that Svelte can't infer what properties to expose when creating a custom element. Consider destructuring all the props or explicitly specifying the `customElement.props` option.
https://svelte.dev/e/custom_element_props_identifier(custom_element_props_identifier)  svelte/valid-compile

/Users/Kohei/Sites/sveltia-cms/src/lib/components/common/page-container.svelte
  21:5  error  Using a rest element or a non-destructured declaration with `$props()` means that Svelte can't infer what properties to expose when creating a custom element. Consider destructuring all the props or explicitly specifying the `customElement.props` option.
https://svelte.dev/e/custom_element_props_identifier(custom_element_props_identifier)  svelte/valid-compile

/Users/Kohei/Sites/sveltia-cms/src/lib/components/common/page-toolbar/view-switcher.svelte
  23:5  error  Using a rest element or a non-destructured declaration with `$props()` means that Svelte can't infer what properties to expose when creating a custom element. Consider destructuring all the props or explicitly specifying the `customElement.props` option.
https://svelte.dev/e/custom_element_props_identifier(custom_element_props_identifier)  svelte/valid-compile

✖ 8 problems (8 errors, 0 warnings)

System Info

-

Severity

annoyance

[Rich-Harris]

Transferred issue to eslint-plugin-svelte

[kyoshino]

I cannot upgrade eslint-plugin-svelte to v3 because I’m waiting for eslint-config-airbnb-base to support ESLint v9, which requires the new flat config format, but thanks for the fix anyway! 👏🏼