Next.js - module not found when importing TypeScript module

[arcticmatt]

Here's my code:

// lib/test2.ts

export function test2() {
  console.log("test2");
}

// pages/index.tsx

import { GetServerSideProps } from "next";
// works
import { test } from "../lib/test.js";
// error
import { test2 } from "../lib/test2.js";

export const getServerSideProps: GetServerSideProps = async ({
  req,
}): Promise<{ props: {} }> => {
  test();
  test2();
  return { props: {} };
};

export default function Home(props: {}) {
  return <div>Hi</div>;
}

When I run this code, I get

Module not found: Can't resolve '../lib/test2.js' in '/Users/USER/Documents/software/nextjs-test/pages'

I'm not sure why. Shouldn't lib/test2.ts compile to lib/test2.js, and the import should be fine? I suppose I'm not very familiar with how the imports actually get resolved when TypeScript is in the mix.

Link to all the code here: https://github.com/arcticmatt/nextjs-test

[arcticmatt]

I posted an answer here https://stackoverflow.com/questions/63408148/next-js-module-not-found-when-importing-typescript-module/63421184#63421184