TypeError：无法从undefined中读取属性“contentDetails”

Question

我正在尝试从某些播放列表中获取一些YouTube视频ID。循环开始但最终我看到主题行中的错误（在此行：var videoID = jsonVideoListResult.items [j] .contentDetails.videoId;）。

记录器结果也低于此值。我是GAS的新手，谢谢你的帮助！

[17-05-05 20:39:33:921 EDT] VideoListResult: [object Object]
[17-05-05 20:39:33:922 EDT] VideoID: _R-mvxYzOo8
[17-05-05 20:39:33:982 EDT] VideoListResult: [object Object]
[17-05-05 20:39:33:983 EDT] VideoID: -oqQxOv9HHM
[17-05-05 20:39:34:037 EDT] VideoListResult: [object Object]
[17-05-05 20:39:34:037 EDT] VideoID: WV_I9rvrzsY
[17-05-05 20:39:34:077 EDT] VideoListResult: [object Object]


//get each playlist in the array and get its video ids
  var videoIdArray = [];
  for (var j=0; j<playlists.length; j++) {

  var videoURLprefix = 'https://www.googleapis.com/youtube/v3/playlistItems?part=contentDetails&maxResults=50&playlistId=';
  var videoURLsuffix = '&fields=items%2FcontentDetails%2FvideoId&key=';
  var playListID = String;
      playListID = playlists[j];
      //Logger.log(playListID);

  var getVideo = UrlFetchApp.fetch(videoURLprefix + playListID + videoURLsuffix + apiKey);

  var jsonVideoListResult = [];
      jsonVideoListResult = JSON.parse(getVideo);
    Logger.log("VideoListResult: " + jsonVideoListResult);
  var videoID = jsonVideoListResult.items[j].contentDetails.videoId;
  Logger.log("VideoID: " + videoID);
  videoIdArray.push(videoID); 

  }