Cate Le Bon invented “Crab Day” as a cheery, eccentric alternative to April Fool’s Day. It’s a beautifully fitting name for her fourth album. Crab Day finds the Welsh artist in rarefied indie air: this is a playful, abstract record full of lyrical sharp turns, twitchy cleverness, and nimble post-punk grooves set off by those richly accented vocals a move to L.A. hasn’t dimmed. What her California emigration has provided is some sonic sunshine. The jiving title track, wonky “Wonderful,” and twinkling “Yellow Blinds, Cream Shadows,” in particular, feel like liberated recipients of some joyous creative abandonment.