Patched `fetch` breaks `Request`: `If request is made from ReadableStream, mode should be "same-origin" or "cors"`

### Link to the code that reproduces this issue https://codesandbox.io/p/devbox/compassionate-gauss-n9vpz8 ### To Reproduce 1. Follow the link to the [codesandbox app](https://codesandbox.io/p/devbox/compassionate-gauss-n9vpz8) 2. Run a preview 3. Navigate to a segmented route by clicking the `Go to "/app/[pageId]/page.tsx"` link on the main page 4. Wait and see the error: `If request is made from ReadableStream, mode should be "same-origin" or "cors"` Additional steps, which prove that the request itself is valid when is made without a `Request` object: 1. Open `/app/[pageId]/page.tsx` in the editor 2. Comment the line `await fetchWithRequest();` 3. Uncomment the line `await fetchWithoutRequest();` 4. Run the app again -> no error ### Current vs. Expected behavior Consider an example (**App Router**): ```js const fetchWithRequest = () => { const req = new Request("https://example.com", { mode: "no-cors", method: "POST", body: "", }); return fetch(req); }; export const generateStaticParams = async () => { await fetchWithRequest(); return []; }; ``` ## Current When the `fetch` is called with a `Request` object with `mode: no-cors` option, Next.js throws a error: `If request is made from ReadableStream, mode should be "same-origin" or "cors"` This happens because Next.js patches `fetch` and wraps the client's original `Request` instance with its own (the line 776): https://github.com/vercel/next.js/blob/808d711bcdfa1dd9d152fe03c5e57f355460b657/packages/next/src/server/lib/patch-fetch.ts#L766-L777 The thing is that in case when `._ogBody` (the line 769) property is nullish, the `.body` property of the original `Request` is already a `ReadableStream` (because the `body getter` always returns [a stream or null](https://github.com/nodejs/undici/blob/ab6ea16e3c3e75e979b13ceba8008e45d699852e/lib/web/fetch/request.js#L746)) instead of the initial string: `body: ""`. And this causes the error, because `ReadableStream` can't be used with `mode: no-cors`. …