Strict mode

A setting that makes a type checker stop trusting you in the places it otherwise would. The one that matters most: with it off, a value that could be missing is treated as if it were always there, so the crash waits until the program runs.

An agent only knows what the checker tells it. With strict off it is told nothing about a missing value, so it has no reason to handle one. Turning it on costs almost nothing on a new project. On an old one it can raise a flood of errors at once, which is a job for a ratchet.