Some questions about DoesForEach

[10-days-till-xmas]

With DoesForEach, does OnError run separately for each action? And also, is the enumerable factory ran once and stored before all the tasks begin, or is it enumerated over (basically i want to be able to update the enumerable, removing an item if it throws). I am trying to have a tree-like build system that will act upon several different items. the image below kind of shows what im trying