- 当前 Bug 的表现（可附上截图）

ext_json有不存在的路径

- 预期表现

上传小程序代码

- 复现路径

https://api.weixin.qq.com/wxa/modify_domain?access_token=13_RKXq2bssCvvY-2lp80WUFugwR6P7Dnvu8S95C84ak4cv3SV4-McVl3t8c1s7WQEpwJI_tUhlVaa_s4GlHySrYNXIBYc3xJXFGRw0bDThiDx9yHptAQWAZt8CnRpYQAogQ8FmJNVSSFDhnCXhUKMjAHDIYA

post参数：{user_desc=第三方上传, user_version=V1.0, ext_json={"ext":{"postUrl":"https://wx.xcx02.com/","companyId":3019,"akey":"OOFBZ-DW233-JX33Q-YDCS2-2FBOO-TOF23","appId":"wxa6662828b8427a87","type":"mall","storeId":3019},"extAppid":"wxe9da2a9c12e5da80"}, template_id=9}

- 提供一个最简复现 Demo