When I run npm run dev I get the:

TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" for /home/projects/app/src/app.ts

I could fix it by changing this line in the package.json:

"dev": "ts-node ./src/app.ts"

into

"dev": "ts-node-esm ./src/app.ts"

It doesn't do HMR however, but maybe that wasn't the intention.