If you thought trauma-comedy reached its limit with Hannah Gadsby’s Nanette, buckle up: the American comic Avital Ash is here to workshop her suicide note. A neat idea for gallows-humour standup, right? So you might think, until the tears well up in Ash’s eyes. There is lots to recommend this Edinburgh debut by the Florida native: Ash’s pin-sharpness and devilry; the audacity of her conceit, and how near the knuckle she takes it. Until she takes it too far, into territory the 37-year-old appears still to find upsetting – which makes it hard to laugh along. There is no pretence...