未捕获的TypeError：无法读取未定义的属性“sync”

Question

所以我有这个代码，我尝试设置分数。

var score = 0;
chrome.storage.sync.set({"playerScore": score});

我的manifest.json文件中启用了存储，所以不是这样。对不起，如果解决方案很明显，我还是比较新用的。

清单文件

{
"manifest_version": 2,

"name": "Red Dot",
"description": "This extension is a quick little game I made. It is worthless, 
but it should provide you with at least 5 seconds of entertainment.",
  "version": "1.0",

  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab",
    "storage"
  ]
}

该脚本名为“script.js”，用于“popup.html”文件。