No error in either the admission or the exclusion of evidence and no error or defect in any ruling or order, or in anything done or omitted by the court or by any of the parties, is ground, for granting a new trial or for setting aside a verdict or for vacating, modifying or otherwise disturbing a judgment or order unless it appears to the court that the denial of such relief would be inconsistent with substantial justice. The court at every stage of the proceeding must disregard any error or defect in the proceeding that does not affect the substantial rights of the parties.