Solved Config error

Hello, i have this error code

PHP:

        $check = $this->config->get($rank);
        if(!$this->config->exists($check)){
            $this->getLogger()->critical("Phát hiện lỗi. Lỗi: Không tìm thấy $rank! Tiến hành khởi tạo...");
            $this->config->set($rank, ["Message" => ""]);
            $this->config->save();


My config file

Code:

---
Guest:
  Message: oqo
...

Error:

Code:

2019-04-12 [22:05:08] [Server thread/INFO]: [StaffChat] <Staff> MrDinoDuck connected
2019-04-12 [22:05:08] [Server thread/CRITICAL]: ErrorException: "Illegal offset type in isset or empty" (EXCEPTION) in "src/pocketmine/utils/Config" at line 478
2019-04-12 [22:05:08] [Server thread/DEBUG]: #0 src/pocketmine/utils/Config(478): pocketmine\utils\Utils::errorExceptionHandler(integer 2, string Illegal offset type in isset or empty, string phar://C:/Users/Administrator/Desktop/Minecraft/Frostlands SkyWars/PocketMine-MP.phar/src/pocketmine/utils/Config.php, integer 478, array Array())
2019-04-12 [22:05:08] [Server thread/DEBUG]: #1 plugins/AdvancedVIPJoinMessage/src/MrDinoDuck/AdvancedVIPJoinMessage/Main(30): pocketmine\utils\Config->exists(array Array())
2019-04-12 [22:05:08] [Server thread/DEBUG]: #2 plugins/AdvancedVIPJoinMessage/src/MrDinoDuck/AdvancedVIPJoinMessage/Main(47): MrDinoDuck\AdvancedVIPJoinMessage\Main->checkRank(pocketmine\Player object, string Guest)
2019-04-12 [22:05:08] [Server thread/DEBUG]: #3 src/pocketmine/plugin/MethodEventExecutor(38): MrDinoDuck\AdvancedVIPJoinMessage\Main->onJoin(pocketmine\event\player\PlayerJoinEvent object)
2019-04-12 [22:05:08] [Server thread/DEBUG]: #4 src/pocketmine/plugin/RegisteredListener(98): pocketmine\plugin\MethodEventExecutor->execute(MrDinoDuck\AdvancedVIPJoinMessage\Main object, pocketmine\event\player\PlayerJoinEvent object)
2019-04-12 [22:05:08] [Server thread/DEBUG]: #5 src/pocketmine/event/Event(99): pocketmine\plugin\RegisteredListener->callEvent(pocketmine\event\player\PlayerJoinEvent object)
2019-04-12 [22:05:08] [Server thread/DEBUG]: #6 src/pocketmine/Player(1081): pocketmine\event\Event->call()
2019-04-12 [22:05:08] [Server thread/DEBUG]: #7 src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter(297): pocketmine\Player->doFirstSpawn()
2019-04-12 [22:05:08] [Server thread/DEBUG]: #8 src/pocketmine/network/mcpe/protocol/SetLocalPlayerAsInitializedPacket(45): pocketmine\network\mcpe\PlayerNetworkSessionAdapter->handleSetLocalPlayerAsInitialized(pocketmine\network\mcpe\protocol\SetLocalPlayerAsInitializedPacket object)
2019-04-12 [22:05:08] [Server thread/DEBUG]: #9 src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter(109): pocketmine\network\mcpe\protocol\SetLocalPlayerAsInitializedPacket->handle(pocketmine\network\mcpe\PlayerNetworkSessionAdapter object)
2019-04-12 [22:05:08] [Server thread/DEBUG]: #10 src/pocketmine/network/mcpe/protocol/BatchPacket(119): pocketmine\network\mcpe\PlayerNetworkSessionAdapter->handleDataPacket(pocketmine\network\mcpe\protocol\SetLocalPlayerAsInitializedPacket object)
2019-04-12 [22:05:08] [Server thread/DEBUG]: #11 src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter(109): pocketmine\network\mcpe\protocol\BatchPacket->handle(pocketmine\network\mcpe\PlayerNetworkSessionAdapter object)
2019-04-12 [22:05:08] [Server thread/DEBUG]: #12 src/pocketmine/Player(3114): pocketmine\network\mcpe\PlayerNetworkSessionAdapter->handleDataPacket(pocketmine\network\mcpe\protocol\BatchPacket object)
2019-04-12 [22:05:08] [Server thread/DEBUG]: #13 src/pocketmine/network/mcpe/RakLibInterface(170): pocketmine\Player->handleDataPacket(pocketmine\network\mcpe\protocol\BatchPacket object)
2019-04-12 [22:05:08] [Server thread/DEBUG]: #14 vendor/pocketmine/raklib/src/server/ServerHandler(99): pocketmine\network\mcpe\RakLibInterface->handleEncapsulated(string 192.168.1.5 61612, raklib\protocol\EncapsulatedPacket object, integer 0)
2019-04-12 [22:05:08] [Server thread/DEBUG]: #15 src/pocketmine/network/mcpe/RakLibInterface(110): raklib\server\ServerHandler->handlePacket()
2019-04-12 [22:05:08] [Server thread/DEBUG]: #16 src/pocketmine/network/mcpe/RakLibInterface(100): pocketmine\network\mcpe\RakLibInterface->process()
2019-04-12 [22:05:08] [Server thread/DEBUG]: #17 vendor/pocketmine/snooze/src/SleeperHandler(123): pocketmine\network\mcpe\RakLibInterface->pocketmine\network\mcpe\{closure}()
2019-04-12 [22:05:08] [Server thread/DEBUG]: #18 vendor/pocketmine/snooze/src/SleeperHandler(85): pocketmine\snooze\SleeperHandler->processNotifications()
2019-04-12 [22:05:08] [Server thread/DEBUG]: #19 src/pocketmine/Server(2328): pocketmine\snooze\SleeperHandler->sleepUntil(double 1555081508.7457)
2019-04-12 [22:05:08] [Server thread/DEBUG]: #20 src/pocketmine/Server(2186): pocketmine\Server->tickProcessor()
2019-04-12 [22:05:08] [Server thread/DEBUG]: #21 src/pocketmine/Server(1765): pocketmine\Server->start()
2019-04-12 [22:05:08] [Server thread/DEBUG]: #22 src/pocketmine/PocketMine(250): pocketmine\Server->__construct(BaseClassLoader object, pocketmine\utils\MainLogger object, string C:\Users\Administrator\Desktop\Minecraft\Frostlands SkyWars\, string C:\Users\Administrator\Desktop\Minecraft\Frostlands SkyWars\plugins\)
2019-04-12 [22:05:08] [Server thread/DEBUG]: #23 (1): require(string phar://C:/Users/Administrator/Desktop/Minecraft/Frostlands SkyWars/PocketMine-MP.phar/src/pocketmine/PocketMine.php)

Please help

 

PHP:

$check = $this->config->get($rank);
if(!$check){

 

thanks!