setTimeout回调方法中调用promptAction.showToast报错Internal error. UI execution context not found.

@Entry  
@Component  
struct Index {  
  @State message: string = '从窗口实例中获取UI实例，通过UI实例使用接口';  
  aboutToAppear(): void {  
    setTimeout(() => {  
      //抓取异常  
      try {  
        this.getUIContext().getPromptAction().showToast({  
          message: '弹窗测试',  
          duration: 2000  
        })  
      } catch (e) {  
        console.error("弹窗异常,异常信息:"+JSON.stringify(e))  
      }  
    },1000)  
  }  
  
  build() {  
    Column(){  
      Text(this.message)  
        .id('HelloWorld')  
        .fontSize(15)  
        .fontWeight(FontWeight.Bold)  
        .textAlign(TextAlign.Center)  
        .width('100%')  
    }  
    .width('100%')  
  }  
}