feat(config): friendly ESM file require error

[sapphi-red]

Description

When importing an CJS package from the config, Vite throws the following errors.

X [ERROR] Failed to resolve entry for package "@sveltejs/vite-plugin-svelte". The package may have incorrect main/module/exports specified in its package.json: No known conditions for "." specifier in "@sveltejs/vite-plugin-svelte" package [plugin externalize-deps]

failed to load config from D:\documents\GitHub\vite\playground\alias\vite.config.js
error when starting dev server:
Error [ERR_REQUIRE_ESM]: require() of ES Module D:\documents\GitHub\vite\node_modules\.pnpm\slash@5.1.0\node_modules\slash\index.js from D:\documents\GitHub\vite\playground\alias\vite.config.js not supported.
Instead change the require of index.js in D:\documents\GitHub\vite\playground\alias\vite.config.js to a dynamic import() which is available in all CommonJS modules.

These errors seems to be confusing for the users: https://github.com/sapphi-red/vitepress-plugins/issues?q=is%3Aissue+ERR_REQUIRE_ESM+is%3Aclosed, #13255, https://github.com/Subwaytime/vite-aliases/issues?q=is%3Aissue+is%3Aclosed+%22Failed+to+resolve+entry+for+package%22, https://github.com/sveltejs/vite-plugin-svelte/issues?q=is%3Aissue+%22Failed+to+resolve+entry+for+package%22

This PR changes the error message to tell what happened and what needs to be done.

X [ERROR] "slash" resolved to an ESM file. ESM file cannot be loaded by `require`. See http://vitejs.dev/guide/troubleshooting.html#this-package-is-esm-only for more details. [plugin externalize-deps]

X [ERROR] Failed to resolve "@sveltejs/vite-plugin-svelte". This package is ESM only but it was tried to load by `require`. See http://vitejs.dev/guide/troubleshooting.html#this-package-is-esm-only for more details. [plugin externalize-deps]

I hope this would unblock plugins to migrate to ESM only.

Additional context

---

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.
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• 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.

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[patak-dev]

Looks great! Just some naming nitpicks. Cheers for an ESM only future 🙏🏼

[bluwy]

Looks like a nice addition. FWIW I've also raised this in node without much conclusion: https://github.com/orgs/nodejs/discussions/46379. I've been leaning towards using "default" condition in ESM-only packages to workaround this though.