What amazes me about CS - and this almost literally leaves me speechless - is how little interest there is in classifying and avoiding bugs, and working towards a General Theory of Why Stuff Might Not Work. Even a set of basic widely accepted heuristics would be good.

Instead of real observation, there's a lot of leaning on type theory, OOP, immutability, and other ideas that scratch some sort of neatness itch and/or advance the careers of opinionated language creators, but have little/no empirical support to prove they actually produce more reliable code.

Meanwhile formal techniques and languages that do have empirical support are sidelined and ignored.

Bugs like yours are not uncommon. If anything, because of Darwinian debugging - the obvious ones die first - you'd expect a good proportion of hard-to-reproduce bugs in any code base.

So they shouldn't be considered weird aberrations. I'm not sure why CS theory doesn't have a better handle on them.

Yes, this amazes me as well. Shallow bugs are many and are fixed quickly and easily so in the end the ones that remain are nasty and hard to fix.

Every anti-bug measure tends to work like yet another brush aimed at a wall. But most brushes overlap partially or even wholly with areas of the wall already painted with previous brushes. The only strategy that would really work would cover all of the wall in a very systematic fashion.