Working as a professional software developer, you will end up with some "legacy" projects. One could call them inherited software; another developer created it, they've moved on, and now you've inherited it.
Sometimes it may be stable and built on sound principles. More often than you'd like, they are buggy and poorly designed, and your challenge as the inheritor is to just keep it running. Starting over from scratch isn't possible, so manage with what you've been given.
This morning, a recent inherited software project finally showed signs of improving. How did it communicate this to me? Instead of generating an average of ten errors overnight during a batch upload, it generated 106 errors. Some people may think more errors is a bad thing, but I do not see it that way. It is a sign that through the small changes I've made to the software - precision pokes and prods - has finally dusted the cobwebs.
It's a little like a house that looks presentable at first, but when you look more closely you find the floor looks clean because the dirt was swept under the rugs, rooms look tidy because all the junk is crammed into the closets, and the paint on the walls hide the mouldering structure. Until you see the flood of error messages, you haven't scratched the surface of the reconstruction.