Oliver Tree Nickell died on June 14 in a helicopter crash in Rio de Janeiro. He was 32. He made music that refused to sit in one genre, “Life Goes On,” “Miss You,” “Alien Boy,” and built a whole visual world around it with the bowl cut and the videos he wrote and directed himself. Earlier this year, on the Zach Sang Show, he laid out exactly what he wanted to happen to everything he’d built. The plan was simple and a little radical. His family, …