fix(typescript-vfs): resolve lib dir via getDefaultLibFilePath so re-export wrappers (@typescript/typescript6) work

[Andrea (andrepav1)]

Problem

createDefaultMapFromNodeModules finds the bundled lib.*.d.ts via path.dirname(require.resolve("typescript")). require.resolve returns the resolved package's entry file, so for a re-export wrapper the directory it points at contains no lib files.

This breaks with the official TypeScript 7.0 side-by-side package @typescript/typescript6 (npm i -D typescript@npm:@typescript/typescript6), whose entry is module.exports = require("@typescript/old"). The real lib.*.d.ts live in the nested @typescript/old/lib/, so the default map is built without the stdlib and the VFS later throws:

TSVFS: A request was made for .../@typescript/typescript6/lib/lib.es2020.d.ts
but there wasn't a file found in the file map.

Any tool that builds a program through createDefaultMapFromNodeModules (e.g. @ark/attest) fails on a project using the TS 7 side-by-side setup.

Fix

Derive the lib directory from the compiler's own getDefaultLibFilePath, which resolves from the executing file path and so follows the re-export to where the stdlib actually lives, instead of require.resolve:

const ts = _ts ?? (require('typescript') as typeof import('typescript'));
const libDir = tsLibDirectory || path.dirname(ts.getDefaultLibFilePath(_compilerOptions));

• Preserves the existing tsLibDirectory override.
• No caller change needed — callers like @ark/attest invoke createDefaultMapFromNodeModules(compilerOptions) with neither _ts nor tsLibDirectory.
• Works for both plain installs and aliased / wrapped installs.

Notes

• createFSBackedSystem further down has the same path.dirname(require.resolve("typescript")) pattern; happy to fix it here too — left out to keep the change focused on the reported path.
• Verified against @typescript/typescript6@6.0.2: getDefaultLibFilePath returns the @typescript/old (typescript@6.0.3) lib dir with all 108 lib.*.d.ts.
• Same layout concern as the closed docs attempt docs(typescript6): note @typescript/old layout for path-based tooling #3620.

[Jake Bailey (jakebailey)]

Does this break browser uses?