One day not so long ago, I was in a meeting listening to a team explain why their service had gone down and taken out a big chunk of a business. They were one of those things that has to exist and work in order for the actual “thing that makes money” to go. Think of delivering pizzas, connecting dog walkers with dogs who need to be walked, that kind of thing.
It turned out they had been crashing every time a request came through for a certain part of the country. That is, not all pizzas, dog walkers, or whatever it was were handled identically, so they had their own city or region configurations. Think of differences in pricing, taxes, features, or whatever. Trying to process a request for this one particular region had caused the entire process to die when it hit a new config that was “bad” somehow.
Read on for the story. This sounds like a boundary issue. Boundaries are messy and need thorough examination to handle as many possible points of failure as is reasonable. Taking seriously the point that it makes the code messy, the answer is not “Don’t do the checks,” but rather “Put the checks in a place where their messiness has a minimal impact on the rest of my beautiful code but still does the important work we need them to do.” Failing that, live with the mess and have a working process.