HarmonyOS拍照后调用openSync方法报错

Button(this.message) 
  .fontSize(50) 
  .fontWeight(FontWeight.Bold) 
  .onClick(() => { 
    this.uri2PixelMap() 
  }) 
Image('data:image/jpeg;base64,' + this.pixel) 
  .width("100%") 
  .height("70%") 
  .border({ width: 1, color: Color.Red }) 
@State pixel: string | undefined = undefined; 
async uri2PixelMap() { 
  try { 
    let pickerProfile: picker.PickerProfile = { 
      cameraPosition: camera.CameraPosition.CAMERA_POSITION_BACK 
    }; 
    let pickerResult: picker.PickerResult = await picker.pick(getContext(this), 
      [picker.PickerMediaType.PHOTO], pickerProfile); 
    console.error("相册返回值=" + pickerResult.resultUri); 
    console.log("the pick pickerResult is:" + JSON.stringify(pickerResult.resultUri)); 
    const tempath = await this.beginScan(pickerResult.resultUri); 
    console.log(tempath) 
    const imageSource: image.ImageSource = image.createImageSource(tempath); 
    const pixelMap: image.PixelMap = await imageSource.createPixelMap(); 
    const imagePackerApi: image.ImagePacker = image.createImagePacker(); 
    let packOpts: image.PackingOption = { format: "image/jpeg", quality: 98 }; 
    imagePackerApi.packing(pixelMap, packOpts) 
      .then((data: ArrayBuffer) => { 
        console.info('packing succeeded.'); 
        let bufferArr = new Uint8Array(data) 
        let help = new util.Base64Helper 
        this.pixel = help.encodeToStringSync(bufferArr) 
        console.log("base64 => " + this.pixel) 
      }).catch((error: BusinessError) => { 
      console.error('packing failed.'); 
    }) 
  } catch (error) { 
    let err = error as BusinessError; 
    console.error(`the pick call failed. error code: ${err.code}`); 
  } 
} 
async beginScan(url: string) { 
  const tempPath = getContext().filesDir + "/" + util.generateRandomUUID() + ".jpg" 
  const file = fileIo.openSync(url, fileIo.OpenMode.READ_ONLY); 
  fileIo.copyFileSync(file.fd, tempPath); 
  return tempPath; 
}