On the Live Demo, the unoconv listener process did become a zombie for some reason.

While unoconv is still working (it creates a dedicated LibreOffice instance in such a scenario), the conversions are way slower.

In order to prevent this from happening, we have to:

1. Check the state of the unoconv listener process.
2. If state is invalid (no such process / zombie), try to restart the listener.
3. If restart fails, /health endpoint should return an error.