(a) Except as provided in AS 13.12.603, a devise, other than a residuary devise, that fails for any reason becomes a part of the residue.
(b) Except as provided in AS 13.12.603, if the residue is devised to two or more persons, the share of a residuary devisee that fails for any reason passes to the other residuary devisee, or to other residuary devisees in proportion to the interest of each in the remaining part of the residue.