Cannot mock fs

[Ghirigoro]

I'm converting a jest setup to vitest and am getting stuck on mocking. In one suite I mock fs with memfs to test some functions that write to disk. My setup is a __mock__ dir with an fs.js file:

import { fs } from "memfs";
module.exports = fs;
// I've also tried: 
// export default fs;

and a test file:

import { vi, beforeEach, describe, expect, it, afterEach } from "vitest";
import * as fs from "fs";
import { vol } from "memfs";
// a bunch of unrelated imports...

vi.mock("fs");

// the tests...

If I include vi.mock("fs") vitest is unable to run the tests with the following error:
TypeError: Cannot read properties of undefined (reading 'dataEmitted')

Is there something I'm missing about how to mock modules?

P.S. - This fails the same way even if I mock fs with fs itself (i.e. export * as fs from "fs"; so there's something I'm doing wrong in the mocking and not an issue with memfs