javascript function listFiles() always return undefine

Can you please post an example of how you're calling the function?

Tasker can access folders normally,but javascript function listFiles() always return undefine.
Tasker veersion : 5.9.3
Android version : 8.0.0 EMUI 8.0.0
Device : Huawei Honor 7C

in old tasker version,listFiles() can return files array object.

my javascript code:

var _bing_base_url_ = "http://www.bing.com/";
var _save_path_ = "/sdcard/BingWallpaper/";


var imgFiles = listFiles( _save_path_ );
var imgFilesArr = imgFiles.split( '\n' );

var wallPaperFile = "";

function getRandomIntInclusive(min, max) {
  min = Math.ceil(min);
  max = Math.floor(max);
  return Math.floor(Math.random() * (max - min + 1)) + min; //The maximum is inclusive and the minimum is inclusive 
}

try {
  var wallPaperFile1 = imgFilesArr[getRandomIntInclusive(0,imgFilesArr.length-1)];
  var wallPaperFile2 = imgFilesArr[getRandomIntInclusive(0,imgFilesArr.length-1)];
  var wallPaperFile_new = imgFilesArr[imgFilesArr.length-1];
  
  var wallPaperFilesArr = [wallPaperFile1,wallPaperFile2,wallPaperFile_new];
  
  wallPaperFile = wallPaperFilesArr[getRandomIntInclusive(0,wallPaperFilesArr.length-1)];
} catch(e) {
  flash('there was an error: ' + e.message);
}

tk.setGlobal("Bingfiles",wallPaperFile);
tk.setGlobal("Bingpaperinfo",wallPaperFile.replace(new RegExp(_save_path_,"gm"),"").replace(new RegExp(".jpg","gm"),""));