app doesn't launch

Likely due to changes in the [Heroku buildpacks](https://community.fly.io/t/heads-up-the-heroku-node-buildpack-might-be-breaking-your-builds/4454) this example no longer works. Cloning and then doing `fly launch` churns a bit and then gives

> ` ERROR: failed to launch: determine start command: when there is no default process a command is required`

I addressed this either by adding a `Procfile` as suggested in the post or by renaming `server.js` to `index.js` and deleting the `main` prop from `package.json`. Not sure which you would prefer. (Personally I like the latter as `Procfile` feels very implemention-ish and can be obscure for people who have not come across it before :hand:.