Sure, that code fails with a memory fault with (safety 0). But I explicitly recommended testing and debugging with (safety 3) first, and in that case it gets a

Sure, that code fails with a memory fault with (safety 0). But I explicitly recommended testing and debugging with (safety 3) first, and in that case it gets a type-error and doesn't crash. Once the broken `(foo nil)` is fixed and it's time to ship a release build to the user, it should be safe to drop down to (safety 0). I think we both agree that 99.9% of the time it's not worth using (safety 0), though.