No act done or proceedings taken under this Act by the Slum Rehabilitation Authority or committee appointed by the Slum Rehabilitation Authority, shall be invalidated merely on the grounds of,—
(a) any vacancy of a member or any defect in the constitution or reconstitution of the Slum Rehabilitation Authority or a committee thereof; or
(b) any defect or irregularity in the appointment of a person as member of the Slum Rehabilitation Authority or of a committee thereof; or
(c) any defect or irregularity in such act or proceedings, not affecting the substance.