fix(device): 添加空值检查避免空指针异常- 在设置设备在线状态时添加对 lastActiveTime 和 clientIP 的空值检查

- 在判断设备是否在线时，增加对 keepaliveAt 时间的空值判断
- 防止因空值导致的 NullPointerException 异常- 提高代码健壮性和稳定性

src/main/java/com/ycwl/basic/service/mobile/impl/AppScenicServiceImpl.java

@@ -294,7 +294,9 @@ public class AppScenicServiceImpl implements AppScenicService {
             if (onlineStatus != null) {
                 deviceRespVO.setUpdateAt(onlineStatus.getKeepaliveAt());
                 deviceRespVO.setKeepaliveAt(onlineStatus.getKeepaliveAt());
-                if (new Date().getTime() - onlineStatus.getKeepaliveAt().getTime() > 300000) {
+                if (onlineStatus.getKeepaliveAt() == null) {
+                    deviceRespVO.setOnline(0);
+                } else if (new Date().getTime() - onlineStatus.getKeepaliveAt().getTime() > 300000) {
                     deviceRespVO.setOnline(0);
                 } else {
                     deviceRespVO.setOnline(onlineStatus.getOnline());