Warning
Not tested after Mojave!
PR welcome.
Simple stupid app used to fix the sound issues (read below) while using an external HDMI monitor on macOS for video only, and perhaps the other sound-related issues. If you find it working for other issues, please report back or create a pull request with them on README.md :)
This bug occurs occasionally when you attach a HDMI monitor to your Macbook, and using the HDMI for video output only - so, you still use your primary sound output device as default. The sound on primary output becomes mute randomly and it ignores any user actions such as (un)Mute, Volume Up, Volume Down, changing the default output device, attaching headphones etc.
It can either be fixed by rebooting the system, OR by killing the system's coreaudiod daemon.
This is basically what this app does - it restarts the sound daemon.
After clicking on the Skull, the app kills coreaudiod, and the system automatically restarts the daemon afterwards, and your sound is back to normal 🎼
After the successful daemon restart, the app closes on itself and you're done 
This software is released under the GPL-3.0