angular 6 with Fabricjs update polyline points error

Question

I am using angular 6 with fabricjs 2.6 for a connector app where object connects with a polyline. After updating polyline points, I am unable to select the connector line or disappear on canvas zoom. I already used the setCoords method, but can't select polyline.

line.points[3]=(new fabric.Point(midX,newEndPoint.y));
newEndPoint=line.points[3];
line.dirty = true;
line.setCoords();
this.Canvas.renderAll();