Line 99 is just for you to know you have to add it at the end, between the layers tag and the c2 layout tag.
As for why, as I said in my post above, there's a bug that requires any object type to have an original instance in a layout.
This applies to arrays too, but it is harder to see as they are "nonworld" type of objects, they don't have a displayed instance in any layout.
But still, their layout of creation is also their layout of initialisation.
So if you create an array object on a layout, and later destroy this layout from your project, the array has no original instance anymore, and you can't create another instance (this is by design for nonworld instances I think, like you need only one "Keyboard" for all your project; all should be resolved once the "original instance bug" is fixed, on Ashley's todo list already).
Also I forgot : the edited capx