Chapter: quality
Rule: throwInsteadOfInvalid
Spec: Threw instead of invalid
A value that should have been a field error crashed the page instead (uncaught JavaScript). The tab can die; users never see a red field.
Example: a date or number field gets junk and the script throws (Invalid time value) instead of marking the field invalid. Same missing validation as Q-02, different outcome: crash, not stored data. A generic page crash with no junk fill is still pageError, not this id.
This id is stable. Reports link here so T/V/Q classes do not shuffle when a soak ranks differently.