[MQTTMessage] missing suback variable header

[shenhuagege]

if (type == MQTTSuback) {
if (message.data.length < 3) {
DDLogWarn(@"[MQTTMessage] missing suback variable header");
message = nil;
}
}

The server returns data is <90020002>
message.data is <0002>
the log is :
2022-05-31 18:14:16.992163+0800 YSTMqttSDK_Example[3152:267773] -[YstMQTTWebsocketManager handleEvent:event:error:]MQTT 不可接受的协议
2022-05-31 18:14:16.992608+0800 YSTMqttSDK_Example[3152:267773] -[YstMQTTWebsocketManager handleEvent:event:error:]链接报错 -- Error Domain=MQTT Code=-7 "MQTT illegal message received" UserInfo={NSLocalizedDescription=MQTT illegal message received}
2022-05-31 18:14:16.993296+0800 YSTMqttSDK_Example[3152:267773] -[YstMQTTWebsocketManager handleEvent:event:error:]MQTT链接关闭
Did the server return the wrong data?