Your last messages about debugging motivated me to do some stuff as well. I found this requesting nits when no mapping exists line interesting as well and when I Ducked/Googled it I got back to this topic 
I see the error pop up quite often. When the screen times out and when the screen is turned on again. But also indeed when the brightness error is triggered when e.g. calling. Which I guess relates more to the issue below. But might also be completely unrelated since the error line seems to happen all the time, but not one of the those bugs themselves occur.
So then I tried my old Google Pixel 3. Ran the same command and filtered only for the Error log level and above that with adb logcat -s *:E, as I also did with my Fairphone 4. And wow, the difference is day and night. On the Pixel there are hardly ANY errors. On the Fairphone 4 you get to see so many of the error tags it’s almost as if it’s a demo of logcat or as if I enabled a low level debug mode. But even worse, I excluded info level logs and such… I knew Fairphone was bad, but jezzzzz.
Anyway, will dig into this more some other time. Maybe I have to setup an Elastic Search cluster to make sense of this amount of errors 