fix: define stubs for react-refresh in Web Worker

[eyr1n]

Description

This PR fixes the issue below and improves #181.
Also the issue is mentioned in vitejs/vite#5396 (comment)

Define some stubs in Web Worker which is required by react-refresh to avoid the error: Uncaught ReferenceError: $RefreshReg$ is not defined.

Issue

First, create Worker.tsx with the following content

function Worker() {
  return <></>;
}

Then, load Worker.tsx from App.tsx

const worker = new Worker(new URL("./Worker.tsx", import.meta.url), {
  type: "module",
});

In that case, we got the error below

Uncaught ReferenceError: $RefreshReg$ is not defined

Additional context

To avoid this error, @react-three/offscreen package, which renders React Three Fiber to OffscreenCanvas, shows the workaround to downgrade vite-plugin-react and disable all HMR.
This provides bad development experiences, so I hope that a new version will be released soon.

Reference:
https://github.com/pmndrs/react-three-offscreen?tab=readme-ov-file#vite

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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• Read the Contributing Guidelines.
• Read the Pull Request Guidelines and follow the PR Title Convention.
• Check that there isn't already a PR that solves the problem the same way to avoid creating a duplicate.
• Provide a description in this PR that addresses what the PR is solving, or reference the issue that it solves (e.g. fixes #123).
• Ideally, include relevant tests that fail without this PR but pass with it.

[eyr1n]

Can anyone review this?

[ArnaudBarre]

Does this feature is used to render part of a React tree of the whole tree? Because as said here the v3 hack is actually just using raw Vite without plugin. Do you expect any HMR to work after this PR?

[eyr1n]

@ArnaudBarre We are hoping that a part of the React tree will render correctly, not the whole React tree.

I'm using @react-three/offscreen on a small part of my application configured with Vite and don't expect HMR to work correctly in Web Worker because I don't make many changes to this part(offscreen) of the application.

However, I believe that disabling HMR for the whole application just because of packages like @react-three/offscreen would lose value. Therefore, I believe that providing such a stub while HMR is not yet implemented in Web Worker will help many users.

I'm sorry, it was just my project configuration that was wrong, I had missed a check for a file to be used in the worker, and once I properly excluded it, the code worked correctly.
You may close this PR.

[ArnaudBarre]

For anyone coming here, please provide a example of how adding this kind of check could lead to a better DX than just having bare Vite without plugins (which was what people experienced with v3 + disableFastRefresh)