2450. A designation or revocation contained in a will that is null by reason of a defect of form is not null for that sole reason; such a designation or revocation is null, however, if the will is revoked.
A designation or revocation made in a will does not avail against another designation or revocation subsequent to the signing of the will. Nor does it avail against a designation prior to the signing of the will unless the will refers to the insurance policy in question or unless the intention of the testator in that respect is manifest.