ERROR TypeError: Cannot read property 'fromObject' of undefined

[ashishradadia]

i am adding custom object like arrow from blow code drow arrow is working fine
but when i retrieved from json it will gives me error

ERROR TypeError: Cannot read property 'fromObject' of undefined
at fabric.js:1062

below is my code for draw arrow

 this.LineWithArrow = fabric.util.createClass(fabric.Line, {
      type: 'lineWithArrow',
      hasBorders: false,
      hasControls: true,

      _getCacheCanvasDimensions() {
        var dim = this.callSuper('_getCacheCanvasDimensions');
        dim.width += 15; 
        dim.height += 15;
        return dim;
      },

      _render(ctx) {
        this.callSuper('_render', ctx);
        ctx.save();
        const xDiff = this.x2 - this.x1;
        const yDiff = this.y2 - this.y1;
        const angle = Math.atan2(yDiff, xDiff);
        ctx.translate((this.x2 - this.x1) / 2, (this.y2 - this.y1) / 2);
        ctx.rotate(angle);
        ctx.beginPath();
        // Move 5px in front of line to start the arrow so it does not have the square line end showing in front (0,0)
        ctx.moveTo(this.strokeWidth * 2, 0);
        ctx.lineTo(this.strokeWidth * -1.5, this.strokeWidth * 1.5);
        ctx.lineTo(this.strokeWidth * -1.5, this.strokeWidth * -1.5);
        ctx.closePath();
        ctx.fillStyle = this.stroke;
        ctx.fill();
        ctx.restore();
      },
    });

    this.LineWithArrow.fromObject = (object, callback) => {
      callback && callback(new this.LineWithArrow([object.x1, object.y1, object.x2, object.y2], object));
    };