How is it possible to rectify or undo the lapse if it pertains to a vital piece of evidence?

A three-judge bench of Supreme Court has observed in Shivaji Sahabrao Bobade vs. State of Maharashtra (1973) 2 SCC 793 that such an omission does not ipso facto vitiate the proceedings unless prejudice was established by the accused. If the accused succeeds in showing any prejudice it is open to the appellate court to call upon the counsel for the accused to show what explanation the accused has got regarding the circumstances not put to him.

In Basavaraj Patil vs. State of Karnataka (2000) 8 SCC 740 a three-judge bench has followed the aforesaid observation and stated thus:

The above approach shows that some dilution of the rigour of the provision can be made even in the light of a contention raised by the accused that non-questioning him on a vital circumstance by the trial court has caused prejudice to him. The explanation offered by the counsel of the accused at the appellate stage was held to be a sufficient substitute for the answers given by the accused himself.

If such objection was not raised at the appellate stage the revisional court should not normally bother about it. At any rate, the omission to put the question concerning evidence which is purely of a formal nature, is too insufficient for holding that the proceedings were vitiated. The evidence sought to be advanced through the affidavits in this case is, no doubt, only of a formal nature.