Add assertion to NA(t) that t is optional (#3910)
Add assertion to NA(t) that t is optional (#3910)


danking/hail,danking/hail,cseed/hail,danking/hail,cseed/hail,danking/hail,danking/hail,hail-is/hail,hail-is/hail,danking/hail,hail-is/hail,cseed/hail,hail-is/hail,danking/hail,cseed/hail,cseed/hail,hail-is/hail,danking/hail,hail-is/hail,hail-is/hail,cseed/hail,hail-is/hail,cseed/hail,cseed/hail