读取Json错误，JSON parse error: The document root must not follow by other values.

报错截图

ArgumentException: JSON parse error: The document root must not follow by other values.
UnityEngine.JsonUtility.FromJson (System.String json, System.Type type) (at <588829356379400e8d4015563af46ed0>:0)
UnityEngine.JsonUtility.FromJson[T] (System.String json) (at <588829356379400e8d4015563af46ed0>:0)
JsonTools.JsonToObject[T] (System.String fileFullPath) (at Assets/Script/Tools/JsonTools.cs:10)
DebugAssetDatabase.B () (at Assets/Script/Test/Editor/DebugAssetDatabase.cs:80)

{
    "config": {
        "url": "asdlkjfla",
        "updateVersion": "xxxasdlkj",
        "path": "asdklfj",
        "des": "xx"
    },
    "sumSize": 0.0,
    "updateSize": 142.0,
    "bundleInfos": [
        {
            "Url": "",
            "Path": "",
            "MD5": "xxxalksdj",
            "Crc32": 0,
            "ABName": "xx",
            "Size": 0.0,
            "ABDependce": []
        },
        {
            "Url": "",
            "Path": "",
            "MD5": "xxxalksdj",
            "Crc32": 0,
            "ABName": "xx",
            "Size": 0.0,
            "ABDependce": []
        }
    ]
    }
}

public static void WriteJson(object obj,string fileFullPath)
{
        string content = JsonUtility.ToJson(obj, true);

        Debug.Log(content);
        string Dir = Path.GetDirectoryName(fileFullPath);

        if (Directory.Exists(Dir) == false)
        {
            Directory.CreateDirectory(Dir);
        }

        Stream stream = File.Open(fileFullPath, FileMode.OpenOrCreate, FileAccess.Write);
        StreamWriter sw = new StreamWriter(stream, new UTF8Encoding(false));
        sw.Write(content);
        sw.Close();
}