I mean when he sings "there is a light and it never goes out" at the end of the song. He doesn't ever sing this live.
I have bothered, and no, he never does sing it. Only on the recorded version, and the demo.
Morrissey first sang 'There is a Light' live post-Smiths in 2002 and didn't sing the outro lyric then. He also hasn't been singing it on the recent tour. But there were times when he did sing it live, I think around the 2006-2008 period.