Custom shape not filled correctly with WEBGL

p5.js Coding Questions
2

Very weird. Looks like a bug. It depends on the order of the points:

function setup() {
	createCanvas(150, 100, WEBGL);
	smooth();
}

function draw() {
	background(220);
	fill(100);
	beginShape();
	vertex(1, 1);
	vertex(30, 15);
	vertex(60, 2);
	vertex(61, 30);
	vertex(1, 35);
	endShape(CLOSE);
}

a

function setup() {
	createCanvas(150, 100, WEBGL);
	smooth();
}

function draw() {
	background(220);
	fill(100);
	beginShape();
	vertex(30, 15);
	vertex(60, 2);
	vertex(61, 30);
	vertex(1, 35);
	vertex(1, 1);
	endShape(CLOSE);
}

b

Notice I just move the first point to be the last one.

In motion: https://editor.p5js.org/abe/sketches/B1691vDi7

Maybe related?