Types are not generated if hardhat config file is not typescript

[FFdhorkin]

I have a package.json with "type": "module" and am attempting to get Hardhat to play nice with TypeScript and ESM.

I've noticed that if I have a config file hardhat.config.cjs, then it doesn't generate any types. However, if I rename that same file to hardhat.config.cts (with a test patch for hardhat so that it supports this config file), suddenly it generates types. Here's a log to demo this:

╰─ ls hardhat*                                                                                                       ─╯
hardhat.config.cjs

╰─ hardhat clean && hardhat compile                                                                                  ─╯
Compiled 57 Solidity files successfully (evm target: paris).

╰─ mv hardhat.config.cjs hardhat.config.cts                                                                          ─╯

╰─ hardhat clean && hardhat compile                                                                                  ─╯
Generating typings for: 57 artifacts in dir: typechain-types for target: ethers-v6
Successfully generated 134 typings!
Compiled 57 Solidity files successfully (evm target: paris).