After deleting cells in sections, when a section is deleted, this exception was thrown in an unreliable manner. The exception was triggered after deleting 2 sections. On endItemAnimations, an asssert calls that method, which caused a data reload from dataSource, making data inconsistent with current update, thus exception was thrown.

On endItemAnimations there are all necessary asserts to check data consistency, so I thought having an additional exception on this class (it's the only one) was unnecessary.