fix: avoid packageJson without name in resolveLibCssFilename

[Jinjiang]

Description

Fix the issue when there is no package name in package.json.

which causes errors like below:

[vite:css-post] Cannot read properties of undefined (reading '0')
[vite:css-post] Cannot read properties of undefined (reading '0')
    at getPkgName (/.../node_modules/vite/dist/node/chunks/dep-M1IYMR16.js:10488:14)
    at resolveLibCssFilename (/.../node_modules/vite/dist/node/chunks/dep-M1IYMR16.js:50127:30)

[patak-dev]

Why does the package.json doesn't have a name? It is required:

A package.json file must contain "name" and "version" fields.

Maybe we should improve the error instead saying that the package.json is malformed?

[silverwind]

name and version may be required in the docs, but as far as the npm client is concerned {} is a valid package.json, so I suggest to treat is gracefully.

I think those requirements are only enforced for published packages.

[sapphi-red]

I think this part needs to be fixed as well.

vite/packages/vite/src/node/build.ts

Lines 922 to 932 in e8c783f

	const packageJson = findNearestPackageData(root, packageCache)?.data
	const name =
	libOptions.fileName ||
	(packageJson && typeof libOptions.entry === 'string'
	? getPkgName(packageJson.name)
	: entryName)
	if (!name)
	throw new Error(
	'Name in package.json is required if option "build.lib.fileName" is not provided.',
	)

[Jinjiang]

@sapphi-red Just confirm: I saw several test cases particular on packages/noname. Do you think it should be updated to packages/name as well? Thanks.

https://github.com/vitejs/vite/blob/main/packages/vite/src/node/__tests__/build.spec.ts

[sapphi-red]

I think it should be packages/noname as-is, but the resolved name should be updated so that we test the fallback behavior.

[Jinjiang]

Test case updated. I also added an additional packages/vite/src/node/__tests__/packages/package.json to catch the resolver for noname. Please take a look. 🙏

[sapphi-red]

We have findNearestMainPackageData function that skips the package.json without name field. I think swapping findNearestPackageData with it matches the users expectations.

vite/packages/vite/src/node/packages.ts

Lines 161 to 162 in e8c783f

	// Finds the nearest package.json with a `name` field
	export function findNearestMainPackageData(

[sapphi-red]

Sometimes there're nested package.jsons inside a package. This is often used to map require('pkg/dir') to somewhere else (e.g. pkg/dir/dir.js). We don't need this anymore as most bundlers support exports field though.
https://cdn.jsdelivr.net/npm/primevue@4.2.5/button/package.json
The other case I saw was placing package.json only with { "type": "commonjs" } in a directory so that all files in that directory is treated as CJS.

[sapphi-red]

Thanks!