the arrow head disappears when strokeWidth===1

[Fil]

Plot.arrow([{}], { x1: 0, x2: 1, y: 0, strokeWidth: 1 }).plot() : the arrow head disappears

Plot.arrow([{}], { x1: 0, x2: 1, y: 0, strokeWidth: 1.00001 }).plot() : the arrow head is present (same with 0.99999)

reported by @yurivish