Describe the bug

I'm loading a file (call it library.js) through an ESM import, and compiling that import with Vite. Within library.js, Vite seems to be converting top-level references to this into globalThis. This is contrary to the definition of ESM modules, in which this is expected to be undefined. From MDN:

If the source is loaded as a module (for HTML, this means adding type="module" to the <script> tag), this is always undefined at the top level.

This is particularly troublesome because this === undefined is the most standard way to check whether the current context is being treated as ESM, which currently breaks in Vite.

Reproduction

https://stackblitz.com/edit/vitejs-vite-otqedk

Steps to reproduce

$ npm install
$ npx vite build
$ cat dist/vite-starter.js
console.log(`${globalThis} should be undefined}`);

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: 16.14.2 - /usr/local/bin/node
    Yarn: 1.22.19 - /usr/local/bin/yarn
    npm: 7.17.0 - /usr/local/bin/npm
  npmPackages:
    vite: ^4.2.0-beta.1 => 4.2.0-beta.1

Used Package Manager

npm

Logs

No response

Validations

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• 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.