Wrong result when add padding to margined polygons

[parachvte]

I got different results when do padding on original polygon and on margined polygon.

When I add margin and padding on original polygon, everything works fine (White is original polygon, red is margined, green is padded):

But when I add padding on margined polygon, like

const path = [[10, 0], [60, 0], [70, 80], [50, 122], [30, 90], [3, 32]];
path.push(path[0]);

const margined = new Offset(path).margin(5)[0];
const padded = new Offset(margined).padding(10)[0];

I thought it should be something very like

const padded = new Offset(path).padding(5)[0];

But results are