(a) The death of a principal who has executed a written power of attorney, durable or otherwise, shall not revoke or terminate the agency as to the attorney in fact or other person, who, without actual knowledge of the death of the principal, acts in good faith under the power. Any action so taken, unless otherwise invalid or unenforceable, shall bind successors in interest of the principal.
(b) The disability or incapacity of a principal who has previously executed a written power of attorney that is not a durable power shall not revoke or terminate the agency as to the attorney in fact or other person, who, without actual knowledge of the disability or incapacity of the principal, acts in good faith under the power. Any action so taken, unless otherwise invalid or unenforceable shall bind the principal and his successors in interest.