Clarification on White+Dark Scrolls

Since White Scrolls negate any slot failures on an item does that mean that if a Dark Scroll Fails, the 50% chance to destroy the item is null since the White Scroll takes action on negating the slot usage?

It still has a 50% chance to destroy the item.

White scrolls just negate the usage of the slot if the scroll fails. They don't negate failing.