Determines the number of stacked items contained within an inventory object.
- The item to determine the stack count of.
Returns the number of items in a stack attached to oItem. Only items that are the same may be stacked; i.e. two gems of the same name can be stacked, but a sword and an arrow cannot.
Returns 0 if an invalid object is provided for oItem, or if oItem isn't an item (like a creature or a placeable).