(1) Where the subject-matter insured is mortgaged, the mortgagor has an insurable interest in the full value thereof, and the mortgagee has an insurable interest in respect of any sum due or to become due under the mortgage.
     (2) A mortgagee, consignee, or other person having an interest in the subject-matter insured may insure on behalf and for the benefit of other persons interested as well as for his own benefit.
     (3) The owner of insurable property has an insurable interest in respect of the full value thereof, notwithstanding that some third person may have agreed, or be liable to indemnify him in case of loss.