(1) No act done or proceeding takcn und€r this Act shall be questioned on the ground merely of '-
(a) the e stence ofany vacancy in, or any defect in the constitution of the State Urban and Country Ptanning Board or any Local Planning Authority;
(b) any person having ceased to be a member;
(c) any person associated with the State Urban and Country Planaing Board or any Local Planning Authority under section 13 having voted in contravention of the said section; or
(d) the failure to serve a notice on any person, where no substantial injustice has resulted ftom such failure: or
(e) any omission, defect or iregularity not affecting the merits ofth€ case.
(2) Every meeting of the State Urban and Country Planning Board and any Local Planning Authority, the minutes of the proceedings ofwhich have been duly signed as prescribed in sub-section (4) ofsection 6 and section (4) ofsection 12 shall be taken to have been duly convened and to be free &om alldefecs and irregulariry.