Avoid duplicatie errors for same object in group when having nested viewmodels

If you have a situation where a child item has a error and the child
item object is in multiple lists in the parent view model, you don't
want multiple errors.
For example: if you have a list of unfiltered items with one item in
error and you have a computed that you use for filtering all the items,
you only want to show the error once to a user