unity转微信小游戏，隐藏后台时，把数据存储到缓存里。但会报错：

plugin.js:93 JsonException: Can't add a value here

  at LitJson.JsonWriter.DoValidation (LitJson.Condition cond) [0x00000] in <00000000000000000000000000000000>:0 

(env: Windows,mg,1.06.2402040; lib: 3.2.5)

代码如下：

WX.OnHide((res) => {

            WX.SetStorageSync("key", "data");

            });