object is possibly 'undefined'

Question

 this.listenerCircle = new Konva.Circle({

      x: this.dotPosition.x,

      y: this.dotPosition.y,

      radius: this.outerCircleConfig.radius + 30,

      fill: "transparent",

      listening: true,

    });

 

when i use pattern lock in angular it will create some error like object is possibly 'undefined' .i dont know how to solve this.may i know how to solve this issue using angular.

 

Thanks in advance