[Fixed by Myself] Sketch can not End more than once to draw a face.

[Richard20230331]

So the problem is that you can draw a face like this:

const a = new Sketch([0, 0], 0);
a.Start([0, 0]).LineTo([-10, 0]).LineTo([0, 20]).LineTo([0, 0]).End();
a.Face();

But you can not draw a face like this:

a.Start([0, 0]).LineTo([-10, 0]).LineTo([0, 20]).End();
a.Start([0, 20]).LineTo([0, 0]).End();
a.Face();

It seems that there is a problem in Library.js, SketchInstance.End() method:

faceBuilder = new oc.BRepBuilderAPI_MakeFace(this.wires[0]);
for (let w = 1; w < this.wires.length; w++){
faceBuilder.Add(this.wires[w]);
}

It seems wrong to add wires to MakeFace, cuz the render result is always wrong.
I changed the code like this:

let myWire = new oc.BRepBuilderAPI_MakeWire();
for (let w = 0; w < this.wires.length; w++){
myWire.Add(this.wires[w]);
}
faceBuilder = new oc.BRepBuilderAPI_MakeFace(myWire.Wire());

Please let me know if this makes sense or not, I just did it without too much dive with the occ logic.
Now that you can try the code and get the right render result.