Resolution allows extension-less import which is not aligned with package exports field

[hi-ogawa]

Describe the bug

Related: #18290

For a package with following files:

• package.json

{
  "name": "test-dep",
  "private": true,
  "type": "module",
  "exports": {
    "./*": "./*"
  }
}

• bad.js

export default {}

Vite resolves import "test-dep/bad" to /path-to/bad.js.

Though it's likely that such exports map is not common and probably users wrote it unintended, Vite should probably handle this strictly to avoid confusion with other tools.

Reproduction

https://stackblitz.com/github/hi-ogawa/reproductions/tree/main/vite-exports-resolve-auto-extension?file=README.md

Steps to reproduce

• open https://stackblitz.com/github/hi-ogawa/reproductions/tree/main/vite-exports-resolve-auto-extension?file=README.md
• node repro.js succeeds
• node src/entry.js fails

System Info

System:
    OS: Linux 5.0 undefined
    CPU: (8) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
    Memory: 0 Bytes / 0 Bytes
    Shell: 1.0 - /bin/jsh
  Binaries:
    Node: 18.20.3 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 10.2.3 - /usr/local/bin/npm
    pnpm: 8.15.6 - /usr/local/bin/pnpm
  npmPackages:
    vite: latest => 5.4.8

Used Package Manager

pnpm

Logs

No response

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that reports the same bug to avoid creating a duplicate.
• Make sure this is a Vite issue and not a framework-specific issue. For example, if it's a Vue SFC related bug, it should likely be reported to vuejs/core instead.
• Check that this is a concrete bug. For Q&A open a GitHub Discussion or join our Discord Chat Server.
• The provided reproduction is a minimal reproducible example of the bug.

[sapphi-red]

enhanced-resolve and oxc-resolver supports this too, so probably Webpack and rspack supports this.
https://stackblitz.com/edit/github-dymfdy?file=webpack.js,oxc.js

esbuild seems to error for this case (repro).

If we fix this, I guess we can add module-sync condition to the default conditions. (related: https://x.com/JoyeeCheung/status/1843346705200353631)