To be fair, anyone who uses a 150 line library without bothering to read it deserves what they get.

And in the spirit of your profile text I'm quite glad for such landmines being out there to trip up those that do blindly ingest all code they can find.

And those will need careful review of any code you want to run on them because no one cares about your weird architecture nor should they have to.

> I appreciate that people want to have some pointless if(depth > 0) check everywhere

An after the fact check would be the wrong way to deal with UB, you'd need to check for < INT_MAX before the increment in order to avoid it.

Which is a great way to turn an overflow into a denial of service as suddenly algorithms that were optimized for simple integer arithmetic slow to a crawl.

You can also just use ubsan if you want the runtime checks for overflows in C/C++, no need to switch languages for this.