关注公众号和发送消息时，推送小程序卡片报错，

请求接口：https://api.weixin.qq.com/cgi-bin/message/custom/send?access_token=36_TOLV0PiW29pETEHWF1R1JSTR4cv7Wg1y9cs4tDaPw1Hkr9hsRL_TNR38CcXCD8E4TzMzGofoAeFwLam8n84a1owDRRyHQpyxTAfDeDb6_dK_vSSzXTp23UXmIUx-eoKm5D6f-L8REUMowK0uFOHhAEABKD

post参数：{\"touser\":\"otcmzwYki_Hido88SnFZK3d4IExI\",\"msgtype\":\"miniprogrampage\",\"miniprogrampage\":{\"title\":\"title\",\"appid\":\"gh_11b1a6818be0\",\"pagepath\":\"pages/self/self\",\"thumb_media_id\":\"1234\"}}

响应：marshaling error: json: unsupported type: func() (io.ReadCloser, error)