Month 13 is out of bounds?
This error is logged on iOS 11 and on macOS 10.13 for sure and I'm not seeing it cause any specific function or problem on any platform.

I'll link to the main question here about "does macOS log too much" since that's an opinion and impression that is worthy of discussion. Some people might feel better if there were no messages unless a really serious condition needs action. Others want even more detail so they can know what's happening / learn / measure. So, it's going to be a tradeoff how these are issues / categorized / used.


Fresh macOS install: Console.app displays errors/faults. Is that to be expected?


One interesting developer that has some tools is Howard Oakley who blogs at https://eclecticlight.co/

His downloads page has two apps of interest (use the left downloads link as the product versions below are beta and may not be current in a day or week):


Consolation - an alternative console browser
Woodpile - a tool to count / bin / analyze patterns of logging