Replaced assert with tw_error() call for lookahead violations.
Replaced assert with tw_error() call for lookahead violations.

laprej/ROSS-CXX,carothersc/ROSS,laprej/ROSS-CXX,carothersc/ROSS,JohnPJenkins/ROSS,carothersc/ROSS,JohnPJenkins/ROSS,JohnPJenkins/ROSS,laprej/ROSS-CXX