`Error while serving connection: connection error` is vague

We encountered some errors of the form:

```
2024-09-30T16:13:18.865613Z ERROR mas_listener::server: crates/listener/src/server.rs:389: Error while serving connection: connection error
```

This error is a bit vague

- 'connection error' could probably be expanded upon
- this should probably include some context about which connection, e.g. the IP address & port of the client at a minimum. Not that this was a concern for us here, but I can easily see it being.