Get Folder Size - App Script

getFolderSize.js

var count = 0;
function myFunction() {

  Logger.log('Starting');
  
  // Please Write the path of the folder you want sub path seperated with slash(,) (spaces are counted)
  // for example: for myFolder/test -> myFolder,test
  // And NOT myFolder, test
  var folders = [];
  if(!folders) {
     return;
  }
  Logger.log('Finished: ' + formatSize(getFolderSize(findFolder(null, folders, 0))));
  
  Logger.log('Count: ' + count);
}

// a - bytes
// b - number after point
function formatSize(a, b) {
  if(0==a)return"0 Bytes";var c=1024,d=b||2,e=["Bytes","KB","MB","GB","TB","PB","EB","ZB","YB"],f=Math.floor(Math.log(a)/Math.log(c));return parseFloat((a/Math.pow(c,f)).toFixed(d))+" "+e[f]
}

function findFolder(parent, folderNames, i) {
  if(folderNames.length - 1 < i) {
   return parent;
  }
  
  var folderName = folderNames[i];
  Logger.log(folderName);
  if(!parent) {
    var folders = DriveApp.searchFolders('title contains "'+folderName+'"');
    parent = folders.next();
  }
  
  
  var foundedFolders = parent.getFolders();
  while (foundedFolders.hasNext()){
    var folder = foundedFolders.next();
    return findFolder(folder, folderNames, i + 1);
  }
}

function getFolderSize(folder) {
  if(!folder) {
   return 0; 
  }
  
  var size = 0;
  
  var files = folder.getFiles();
  while (files.hasNext()){
    var file = files.next();
    count++;
    size +=file.getSize();
  }
  
  var subFolders = folder.getFolders();
  while (subFolders.hasNext()){
    var subFolder = subFolders.next();
    size += getFolderSize(subFolder);
  }
  
  return size;
}

@rluvation It still doesn't work, stil got the same error. Sorry, but with my folder structure My Drive/Chess, how suppose I write it in the code? Is it My Drive,Chess or "My Drive","Chess" or what? Because I'm not good in programming. Thanks.

This is the error that I got.