Hi,
I’ve the same and I think it’s when you watch something on an unknown source (eg Netflix). It is refreshing from an unknown source an empty channel list which gives this error.
I am starting to have this error every time there is a new HASS update. I don’t know how it could be related, but at my RaspberryPi it is related. To fix it, I need to install that pending update, sometimes restart RPi and sometimes even remove “bravia.conf” completely, so HASS reconfigures it again on next boot (the JSON data in the file is always the same and my pin is “0000”). It’s pretty weird and rather annoying. The ticket on GitHub https://github.com/home-assistant/home-assistant/issues/6002 was never addressed and it’s closed now.