Fix draft mode invariant (#62121)
### What?
In today's implementation, requests that don't end in `.rsc` are getting
the data request query. We need to remove this toggle to prevent them
from 500'ing.
### Why?
The invariant triggered was:
https://github.com/vercel/next.js/blob/212553958c671ea1f71d96fbc97ea4b9e5019bf3/packages/next/src/server/base-server.ts#L2838-L2842
Crawling up the code, the conditional:
https://github.com/vercel/next.js/blob/212553958c671ea1f71d96fbc97ea4b9e5019bf3/packages/next/src/server/base-server.ts#L2815
must be `true`.
The variable `isDataReq` is set here:
https://github.com/vercel/next.js/blob/212553958c671ea1f71d96fbc97ea4b9e5019bf3/packages/next/src/server/base-server.ts#L1833-L1839
This conditional expression is a bit complex, but it simplifies down to:
- `isDataReq` is `true` when (TODO)
- `isDataReq` is `false` when (TODO)
### How?
Closes NEXT-2341
Fixes #61377
Tested manually by:
- Building and packaging this branch locally
- Deploying tarball and then depending on it as the Next.js version for
an example app similar to the one reported by #61377
- Inspecting console for 500 errors.
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Co-authored-by: JJ Kasper <jj@jjsweb.site>
Co-authored-by: Zack Tanner <zacktanner@gmail.com>
