next.js

41a80533 - Revert "Don't fail the build if @types/ packages appear to be missing" (#66130)

Revert "Don't fail the build if @types/ packages appear to be missing" (#66130) This reverts commit https://github.com/vercel/next.js/commit/637033c41054ee1d50107b1fd63a91a2051e1653. What wasn't clear originally is that we require that required packages have their `package.json` resolvable. So either they don't have an `exports` field, or their `package.json` is listed in the `exports` field. The React beta types didn't have `package.json` entry in `exports` so we accidentally thought they weren't installed. I published [`19.0.0-beta.2` that has `package.json` in `exports`](https://github.com/eps1lon/DefinitelyTyped/pull/31/commits/13879ee571bd3996ad2dffd58a288e9762bf31d1#diff-81cc573aa0c2bd0e13f9463499747741704aabccd7474f544db710befd7bcfc4R44) so we can restore the old behavior. It's still questionable IMO to do all that I/O work just for a nicer error message that may contain false-positive but that's for another time.