docs: correct the suggested type for custom events without detail (Svelte 4)

[th0rgall]

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Tests and linting

• Run the tests with pnpm test and lint the project with pnpm lint
  Tests are OK, except for those using Playwright, which I didn't install. Linting crashes for me with an Eslint "Cannot find module" error. I'm holding off on fixing these setup issues, I'm not sure if it's worth it for a one-word docs change.

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I tried to follow the guidance given by the docs for createEventDispatcher to type a custom event without a detail argument. The function documentation mentions that the never type can be used for this. However, when doing this, I'm getting a Typescript error Expected 2-3 arguments, but got 1 when calling createEventDispatcher.

I searched the dedicated v4 docs site and found this section on createEventDispatcher which includes event: null; // does not accept a payload. I assume that "payload" & "detail" mean the same thing, and that suggesting to use "never" was a mistake in the function docs (or something that was never updated). With "null" it works as expected!

[changeset-bot]

🦋 Changeset detected

Latest commit: 15b66b5

The changes in this PR will be included in the next version bump.

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[dummdidumm]

You're right, we've tried never at one point but it resulted in problems so we changed it; guess we never changed the docs for it.
You gotta regenerate the types (pnpm generate:types within packages/svelte + commit), then we're good to merge 👍

[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-svelte-15763-svelte.vercel.app/

[th0rgall]

It was a very understandable oversight 🙂 And I didn't realize I had to generate the types, done now!

[github-actions]

Playground

pnpm add https://pkg.pr.new/svelte@15763