HarmonyOS下载文件失败返回

import request from '@ohos.request'; 
@Entry 
@Component 
struct Index { 
  build() { 
    Row() { 
      Column() { 
        Button("downloadFile") 
          .onClick(async () => { 
            try { 
              let downloadTask = await request.downloadFile(getContext(), { 
                url: "https://test1.har", 
                filePath: "internal://cache/test.har", 
              }); 
              downloadTask.on("progress", (receivedSize: number, totalSize: number) => { 
                console.log("progress", receivedSize, totalSize); 
              }); 
              downloadTask.on("complete", () => { 
                console.log("complete"); 
              }); 
              downloadTask.on("fail", (err: number) => { 
                console.log("fail", err) 
              }); 
            } catch (err) { 
              console.log(err); 
            } 
          }) 
      } 
      .width('100%') 
    } 
    .height('100%') 
  } 
}