I use defensive programming, as in throwing errors when something is used the wrong way. Assuming that the developer always run the code at least once before sh

I use defensive programming, as in throwing errors when something is used the wrong way. Assuming that the developer always run the code at least once before shipping. But I try to avoid thinking into the future. I'm already too good at finding edge cases, that if I would also think about possible issues that might arise in the future, I would get nothing done. I instead wait for it, and then fix it only when it has become an issue. Especially in optimization, I often fall into though traps like "what about when this table has millions of rows, this query would take a long time", I have to remind myself of the problem and what the priority is right now. While there is code debt, there is also opportunity cost.