How to correctly import @nomicfoundation/hardhat-chai-matchers into hardhat project?

Question

Following the instructions, I put this in hardhat.config.ts:

import '@nomicfoundation/hardhat-chai-matchers';

In my test I have:

expect(maxCount).to.equal(64);

where maxCount is a BigNumber from ethers.js, and 64 is a regular Javascript/Typescript number.... but I get this error:

AssertionError: expected [ BigNumber { value: "64" } ] to equal 64

... which means that the hardhat chai matcher is not kicking in, as it is supposed to handle the BigNumber by performing the conversion automatically as part of the assertion.

This leads me to think that the way I'm importing this module may be incorrect. What's the proper way?

Technically, the "Usage" section of the docs state it as a CommonJS require:

require("@nomicfoundation/hardhat-chai-matchers");

Since my hardhat config (and rest of project) is in Typescript, I've used this instead:

import '@nomicfoundation/hardhat-chai-matchers';

---

More details:

Here're my dev dependencies from package.json:

  "devDependencies": {
    "@nomicfoundation/hardhat-chai-matchers": "1.0.6",
    "@nomicfoundation/hardhat-toolbox": "2.0.2",
    "@types/chai": "4.3.4",
    "@types/fs-extra": "11.0.1",
    "@types/mocha": "10.0.1",
    "@types/node": "18.14.6",
    "fs-extra": "11.1.0",
    "hardhat": "2.13.0",
    "ts-node": "10.9.1",
    "typescript": "4.9.5"
  }

And here're my run times:

$ node -v
v16.13.1
$ npm -v
8.1.2

---

Edit

In an attempt to debug, I've manually edited node_modules/@nomicfoundation/hardhat-chai-matchers/src/internal/bigNumber.ts to add console.log statements in a couple of spots.

function overwriteBigNumberFunction(
  functionName: Methods,
  readableName: string,
  readableNegativeName: string,
  _super: (...args: any[]) => any,
  chaiUtils: Chai.ChaiUtils
) {
  console.log('hh chai matcher overwriteBigNumberFunction');
  /* ... */

    } else if (isBigNumber(expectedFlag) || isBigNumber(actualArg)) {
      console.log('hh chai matcher bignit');
  /* ... */

Then subsequently run npx hardhat console. Neither of the above log statements are output, leading me further to believe that the way I'm importing isn't right.