vmThreads CommonJS this isn't bound to module.exports #11501

Describe the bug

We hit this loading FlexSearch in vmThreads and narrowed it down to how the VM loader calls CommonJS modules. Top-level this isn't bound to module.exports, as it is in Node. In a strict-mode module, it's undefined.

Reproduction

reproduction.zip

The reproduction uses Vitest 5.0.3, a local CommonJS dependency, and no custom config.

The dependency's index.cjs is:

'use strict';
this.value = 42;
exports.isExports = this === module.exports;

The test:

import { expect, test } from 'vitest';
import commonjs from 'commonjs-this-fixture';

test('binds CommonJS top-level this to exports', () => {
  expect(commonjs).toEqual({ value: 42, isExports: true });
});

This passes in Node and with --pool=threads. With either --pool=vmThreads or --pool=vmForks, it fails during import:

TypeError: Cannot set properties of undefined (setting 'value')

I'd expect it to pass in all three pools.

CommonjsExecutor._compile calls the wrapper without a receiver. Binding it to this.exports makes the test pass in both VM pools:

-fn(this.exports, this.require, this, filename, __dirname)
+fn.call(this.exports, this.exports, this.require, this, filename, __dirname)

The patch was tested against the published 5.0.3 package. The linked main revision has the same call, but hasn't been tested with this patch.

I used Codex to help isolate the problem and test the patch.

System Info

System:
  OS: macOS 26.6.2
  CPU: (18) arm64 Apple M5 Max
  Memory: 443.28 MB / 64.00 GB
  Shell: 5.9 - /bin/zsh
Binaries:
  Node: 22.15.0 - /Users/lee.standen/.volta/tools/image/node/22.15.0/bin/node
  Yarn: 1.22.19 - /Users/lee.standen/.volta/tools/image/yarn/1.22.19/bin/yarn
  npm: 10.9.2 - /Users/lee.standen/.volta/tools/image/node/22.15.0/bin/npm
  pnpm: 11.24.0 - /Users/lee.standen/.volta/bin/pnpm
Browsers:
  Chrome: 154.0.8037.93
  Safari: 26.6.2
npmPackages:
  vitest: 5.0.3 => 5.0.3

Used Package Manager

pnpm

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