Ethan Shanfeld Dave Franco’s character Xavier plummets to his death within the first minute of “The Afterparty.” But there’s plenty more to learn about the dweeb-turned-pop-superstar, whose origins and motivations unravel across eight episodes of Chris Miller and Phil Lord’s whodunnit, which premiered on Apple TV Plus on Jan. 28.While the series only gives viewers a small taste of Xavier’s music, now fans of “The Afterparty” can enjoy four fully produced songs from the fictional artist on his brand new EP, “R.I.P.