I don't disagree that it's hard to know all these shortfalls ahead of time, that's sort of why software has bugs and why all us devs stare in amazement anytime it's suggested "Could you folks just... write less bugs" but when the builds start to fail it should be acknowledged that your tests are incomplete, and it should (ideally) be a high priority task to either revert out the feature or fix the feature to resolve the issue. (There are all sorts of reasons this could be difficult, but I'd urge you to advocate strongly for fixing bugs as a higher priority task than feature work - it ends up saving businesses money)