[LayaAir 2.0]progressbar设置皮肤后, 马上destroy会报bug

set skin(value: string) {

        if (this._skin != value) {

            this._skin = value;

            if (this._skin && !Loader.getRes(this._skin)) {

                ILaya.loader.load(this._skin, Handler.create(this, this._skinLoaded), null, Loader.IMAGE, 1); // TODO TS

            } else {

                this._skinLoaded();

            }

        }

    }



    protected _skinLoaded(): void {

        this._bg.skin = this._skin;

        this._bar.skin = this._skin.replace(".png", "$bar.png");

        this.callLater(this.changeValue);

        this._sizeChanged();

        this.event(Event.LOADED);

    }

 this._bg.skin = this._skin;// 这行会报错