No decree to be reversed or modified for error or irregularity not affecting merits or jurisdiction.

No decree shall be reversed or substantially varied, nor shall any case be remanded, in appeal on account of any misjoinder 1 [or non-joinder] of parties or causes of action or any error, defect or irregularity in any proceedings in the suit, not affecting the merits of the case or the jurisdiction of the Court : 2[Provided that nothing in this section shall apply to non-joinder of a necessary party.]