alt Hacker NewsLLMs can find endless combinations of edge cases that are a real bug. Addressing them requires thousands more lines of code. Which creates another set of new edge cases to combine.
At some point you realize recovery is better then prevention, let the bugs happen, but recover from them gracefully.
That is not usually how it works. Most bugfixes are about the implementation of the logic, not its design, so fixes can be very small changes.