Chris Willman Senior Music Writer and Chief Music Critic Taylor Swift and Ice Spice fans in New Jersey were likely feeling they’d amassed some good karma of their own — at least the ones who had made it through the gauntlet to get tickets for Friday’s MetLife Stadium show — as the suddenly dynamic duo gave the audience two doses of “Karma” toward the end of Swift’s long set. One was in the form of a premiere of the video for the song, which went out to the world not very much later. The other was a live performance of the duet, as the new remix’s featured rapper came out on stage to join the headliner for “Karma,” which has ended Swift’s shows each night since the Eras Tour started in April.