12(1)Where a will is attested by a person to whom or to whose then spouse a beneficial devise, bequest or other disposition or appointment of or affecting real or personal property, except charges and directions for payment of debt, is thereby given or made, the devise, bequest or other disposition or appointment is void so far only as it concerns the person so attesting, or his or her spouse or a person claiming under any of them; but the person so attesting is a competent witness to prove the execution of the will or its validity or invalidity.