arcgis for js 4.23.7 版本 , 新增一个graphic之后 , 无法通过remove方法删除 , 是何原因 ?

mounted () {

      layer = new GraphicsLayer({

        id: this.layerId

      })

      this.drawPoint(this.attributeTemp.longitude, this.attributeTemp.latitude)

    }

  }

drawPoint (x, y) {

      const point = {

        type: 'point', 

        longitude: x,

        latitude: y

      }



      const markerSymbol = {

        type: 'simple-marker', 

        color: [226, 119, 40]

      }

      pointGraphic = new Graphic({

        geometry: point,

        symbol: markerSymbol

      })

      layer.add(pointGraphic)

      this.mapTemp.add(layer)

    }

 beforeDestroy () {

    if (layer) {

      layer.removeAll()

      this.mapTemp.remove(layer)

      layer = null

    }

  }