wx.downloadFile 清除缓存以后再运行小程序，此方法就直接fail报错？
报错信息为："downloadFile:fail Error: ENOENT: no such file or directory, open 'C:\Users\Administrator\AppData\Local\微信开发者工具\User Data\8e3c9a4c80bda5bf8b2d5f0dc11b0f27\WeappSimulator\WeappFileSystem\o6zAJs-ObCuI9J8lUirVaoFx3xGI\wx96821e645ac5476b\tmp\npmRxmrRqMfra0f6c9d27c0648e517b399174fde48c7.png'""downloadFile:fail Error: ENOENT: no such file or directory, open 'C:\Users\Administrator\App[图片]Data\Local\微信开发者工具\User Data\8e3c9a4c80bda5bf8b2d5f0dc11b0f27\WeappSimulator\WeappFileSystem\o6zAJs-ObCuI9J8lUirVaoFx3xGI\wx96821e645ac5476b\tmp\npmRxmrRqMfra0f6c9d27c0648e517b399174fde48c7.png'"
