AthContainers: Early exit from Factory operations for 0 elements.
Exit early from the Factory operations if the number of elements is 0. In particular, don't try to fetch the pointers in that case: in the case of a linked variable, that may fail.
Exit early from the Factory operations if the number of elements is 0. In particular, don't try to fetch the pointers in that case: in the case of a linked variable, that may fail.