S. 143(3): Assessment-Amalgamation-Assessment framed and TPO order passed in the name of a non-existent amalgamating company despite intimation of merger-Subsequent attempt to rectify by invoking s.154 impermissible-Use of expression “formerly known as” shows failure to acknowledge change in legal status-Assessment order a nullity and not curable u/s 292B.[S.92CA(3), 154,260A, 292B]