How a Misconfigured Validation Rule Wasted 40 Minutes of Dev Work

A developer building a configurable form system lost a full editing session after discovering that a validation rule — 'Required' — had a mandatory sub-type dropdown with no default value. The incomplete rule appeared valid within the form editor but was only flagged as broken at the point of saving, after 15+ questions had already been configured. The core problem was that the system could not distinguish between a rule still being set up and one that had been left incomplete, since both stored identically as a null value. The author argues that such issues can be prevented by making invalid states unrepresentable, setting safe defaults, or surfacing errors immediately when a user leaves a half-configured field. All three approaches are preferable to deferring validation to submission, which creates long, frustrating feedback loops for form authors.