Application failed to respond

Question

My code, using fastify:
```ts
import Fastify from 'fastify';
// ...
const port = parseInt(process.env.PORT || '3000', 10);

console.log('Listening on port', port);

app.listen({ port: port }, (err) => {
    if (err) throw err;
});

```
Link: https://substack-production.up.railway.app/
The port should be correct, because it logs the port 8080 and shows 8080 in the deploy settings (see image). No errors in the log at all. Github:
https://github.com/zisra/substack