Originally published at hafiz.dev

On October 12, Nuno Maduro posted that "it's kind of insane how much AI agents love nullables." His maths was simple. Every nullable doubles the number of states your code can be in, so a constructor with ten of them has over a thousand combinations to reason about.

I wanted to see what that looks like in a real codebase, so I ran Larastan against one of mine at every level from 0 to 10. It's a production Laravel SaaS on Laravel 12 and Filament 4, about 25,000 lines across roughly 250 files in app/ , built over the last fifteen months. Most of that code was written by Claude Code, with me reviewing it.

The four real bugs all showed up at level 0. Almost everything above that was typing noise with three causes, and two of them took one line each to fix. The nullables were there too.…