APP资源包升级时，出现如下问题

安装wgt文件失败[10]：File too short to be a zip file: 0 at login.html:339
代码：```javascript
var wgtUrl="http://98.52.9.124:8080/cpimAppService/resources/2.0.0.wgt";
plus.nativeUI.showWaiting("下载wgt文件...");
plus.downloader.createDownload( wgtUrl, {}, function(d,status){
if ( status == 200 ) {
console.log("下载wgt成功："+d.filename);
plus.io.resolveLocalFileSystemURL(d.filename,function(){
alert('a');
},function(){
alert('b')
})
installWgt(d.filename); // 安装wgt包
} else {
console.log("下载wgt失败！");
plus.nativeUI.alert("下载wgt失败！");
}
plus.nativeUI.closeWaiting();
}).start();
function installWgt(path){
plus.nativeUI.showWaiting("安装wgt文件...");
plus.runtime.install(path,{force:true},function(){
plus.nativeUI.closeWaiting();
console.log("安装wgt文件成功！");
plus.nativeUI.alert("应用资源更新完成！",function(){
plus.runtime.restart();
});
},function(e){
plus.nativeUI.closeWaiting();
console.log("安装wgt文件失败["+e.code+"]："+e.message);
plus.nativeUI.alert("安装wgt文件失败["+e.code+"]："+e.message);
});