So, my server somewhat lags upon certain items. And sometimes causes a player to get kicked from the server for flying when they wern't even flying. This is the error I'm getting at the same time:
TypeError: "Return value of pocketmine\nbt\tag\CompoundTag::key() must be of the type string or null, integer returned" (EXCEPTION) in "vendor/pocketmine/nbt/src/tag/CompoundTag" at line 474
04.09 10:09:52 [Server] Server thread/DEBUG #0 vendor/pocketmine/nbt/src/tag/CompoundTag(493): pocketmine\nbt\tag\CompoundTag->key()
04.09 10:09:52 [Server] Server thread/DEBUG #1 vendor/pocketmine/nbt/src/tag/NamedTag(106): pocketmine\nbt\tag\CompoundTag->equalsValue(pocketmine\nbt\tag\CompoundTag object)
04.09 10:09:52 [Server] Server thread/DEBUG #2 src/pocketmine/item/Item(835): pocketmine\nbt\tag\NamedTag->equals(pocketmine\nbt\tag\CompoundTag object)
04.09 10:09:52 [Server] Server thread/DEBUG #3 src/pocketmine/Player(2640): pocketmine\item\Item->equals(pocketmine\item\ItemBlock object)
04.09 10:09:52 [Server] Server thread/DEBUG #4 src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter(136): pocketmine\Player->handleMobEquipment(pocketmine\network\mcpe\protocol\MobEquipmentPacket object)
04.09 10:09:52 [Server] Server thread/DEBUG #5 src/pocketmine/network/mcpe/protocol/MobEquipmentPacket(63): pocketmine\network\mcpe\PlayerNetworkSessionAdapter->handleMobEquipment(pocketmine\network\mcpe\protocol\MobEquipmentPacket object)
04.09 10:09:52 [Server] Server thread/DEBUG #6 src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter(92): pocketmine\network\mcpe\protocol\MobEquipmentPacket->handle(pocketmine\network\mcpe\PlayerNetworkSessionAdapter object)
04.09 10:09:52 [Server] Server thread/DEBUG #7 src/pocketmine/network/mcpe/protocol/BatchPacket(114): pocketmine\network\mcpe\PlayerNetworkSessionAdapter->handleDataPacket(pocketmine\network\mcpe\protocol\MobEquipmentPacket object)
04.09 10:09:52 [Server] Server thread/DEBUG #8 src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter(92): pocketmine\network\mcpe\protocol\BatchPacket->handle(pocketmine\network\mcpe\PlayerNetworkSessionAdapter object)
04.09 10:09:52 [Server] Server thread/DEBUG #9 src/pocketmine/Player(3056): pocketmine\network\mcpe\PlayerNetworkSessionAdapter->handleDataPacket(pocketmine\network\mcpe\protocol\BatchPacket object)
04.09 10:09:52 [Server] Server thread/DEBUG #10 src/pocketmine/network/mcpe/RakLibInterface(162): pocketmine\Player->handleDataPacket(pocketmine\network\mcpe\protocol\BatchPacket object)
04.09 10:09:52 [Server] Server thread/DEBUG #11 vendor/pocketmine/raklib/src/server/ServerHandler(98): pocketmine\network\mcpe\RakLibInterface->handleEncapsulated(string 82.38.148.87 60663, raklib\protocol\EncapsulatedPacket object, integer 0)
04.09 10:09:52 [Server] Server thread/DEBUG #12 src/pocketmine/network/mcpe/RakLibInterface(103): raklib\server\ServerHandler->handlePacket()
04.09 10:09:52 [Server] Server thread/DEBUG #13 src/pocketmine/network/Network(94): pocketmine\network\mcpe\RakLibInterface->process()
04.09 10:09:52 [Server] Server thread/DEBUG #14 src/pocketmine/network/mcpe/RakLibInterface(80): pocketmine\network\Network->processInterface(pocketmine\network\mcpe\RakLibInterface object)
04.09 10:09:52 [Server] Server thread/DEBUG #15 vendor/pocketmine/snooze/src/SleeperHandler(120): pocketmine\network\mcpe\RakLibInterface->pocketmine\network\mcpe\{closure}()
04.09 10:09:52 [Server] Server thread/DEBUG #16 vendor/pocketmine/snooze/src/SleeperHandler(82): pocketmine\snooze\SleeperHandler->processNotifications()
04.09 10:09:52 [Server] Server thread/DEBUG #17 src/pocketmine/Server(2259): pocketmine\snooze\SleeperHandler->sleepUntil(double 1536055792.0863)
04.09 10:09:52 [Server] Server thread/DEBUG #18 src/pocketmine/Server(2134): pocketmine\Server->tickProcessor()
04.09 10:09:52 [Server] Server thread/DEBUG #19 src/pocketmine/Server(1700): pocketmine\Server->start()
04.09 10:09:52 [Server] Server thread/DEBUG #20 src/pocketmine/PocketMine(243): pocketmine\Server->__construct(BaseClassLoader object, pocketmine\utils\MainLogger object, string /, string /plugins/)
04.09 10:09:52 [Server] Server thread/DEBUG #21 /custom-php7.2.phar(1): require(string phar:///custom-php7.2.phar/src/pocketmine/PocketMine.php)
04.09 10:09:52 [Server] RakLibServer thread/NOTICE Blocked 82.38.148.87 for 5 seconds
04.09 10:09:57 [Server] Server thread/CRITICAL TypeError: "Return value of pocketmine\nbt\tag\CompoundTag::key() must be of the type string or null, integer returned" (EXCEPTION) in "vendor/pocketmine/nbt/src/tag/CompoundTag" at line 474
04.09 10:09:57 [Server] Server thread/DEBUG #0 vendor/pocketmine/nbt/src/tag/CompoundTag(493): pocketmine\nbt\tag\CompoundTag->key()
04.09 10:09:57 [Server] Server thread/DEBUG #1 vendor/pocketmine/nbt/src/tag/NamedTag(106): pocketmine\nbt\tag\CompoundTag->equalsValue(pocketmine\nbt\tag\CompoundTag object)
04.09 10:09:57 [Server] Server thread/DEBUG #2 src/pocketmine/item/Item(835): pocketmine\nbt\tag\NamedTag->equals(pocketmine\nbt\tag\CompoundTag object)
04.09 10:09:57 [Server] Server thread/DEBUG #3 src/pocketmine/Player(2640): pocketmine\item\Item->equals(pocketmine\item\ItemBlock object)
04.09 10:09:57 [Server] Server thread/DEBUG #4 src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter(136): pocketmine\Player->handleMobEquipment(pocketmine\network\mcpe\protocol\MobEquipmentPacket object)
04.09 10:09:57 [Server] Server thread/DEBUG #5 src/pocketmine/network/mcpe/protocol/MobEquipmentPacket(63): pocketmine\network\mcpe\PlayerNetworkSessionAdapter->handleMobEquipment(pocketmine\network\mcpe\protocol\MobEquipmentPacket object)
04.09 10:09:57 [Server] Server thread/DEBUG #6 src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter(92): pocketmine\network\mcpe\protocol\MobEquipmentPacket->handle(pocketmine\network\mcpe\PlayerNetworkSessionAdapter object)
04.09 10:09:57 [Server] Server thread/DEBUG #7 src/pocketmine/network/mcpe/protocol/BatchPacket(114): pocketmine\network\mcpe\PlayerNetworkSessionAdapter->handleDataPacket(pocketmine\network\mcpe\protocol\MobEquipmentPacket object)
04.09 10:09:57 [Server] Server thread/DEBUG #8 src/pocketmine/network/mcpe/PlayerNetworkSessionAdapter(92): pocketmine\network\mcpe\protocol\BatchPacket->handle(pocketmine\network\mcpe\PlayerNetworkSessionAdapter object)
04.09 10:09:57 [Server] Server thread/DEBUG #9 src/pocketmine/Player(3056): pocketmine\network\mcpe\PlayerNetworkSessionAdapter->handleDataPacket(pocketmine\network\mcpe\protocol\BatchPacket object)
04.09 10:09:57 [Server] Server thread/DEBUG #10 src/pocketmine/network/mcpe/RakLibInterface(162): pocketmine\Player->handleDataPacket(pocketmine\network\mcpe\protocol\BatchPacket object)
04.09 10:09:57 [Server] Server thread/DEBUG #11 vendor/pocketmine/raklib/src/server/ServerHandler(98): pocketmine\network\mcpe\RakLibInterface->handleEncapsulated(string 82.38.148.87 60663, raklib\protocol\EncapsulatedPacket object, integer 0)
04.09 10:09:57 [Server] Server thread/DEBUG #12 src/pocketmine/network/mcpe/RakLibInterface(103): raklib\server\ServerHandler->handlePacket()
04.09 10:09:57 [Server] Server thread/DEBUG #13 src/pocketmine/network/Network(94): pocketmine\network\mcpe\RakLibInterface->process()
04.09 10:09:57 [Server] Server thread/DEBUG #14 src/pocketmine/network/mcpe/RakLibInterface(80): pocketmine\network\Network->processInterface(pocketmine\network\mcpe\RakLibInterface object)
04.09 10:09:57 [Server] Server thread/DEBUG #15 vendor/pocketmine/snooze/src/SleeperHandler(120): pocketmine\network\mcpe\RakLibInterface->pocketmine\network\mcpe\{closure}()
04.09 10:09:57 [Server] Server thread/DEBUG #16 vendor/pocketmine/snooze/src/SleeperHandler(82): pocketmine\snooze\SleeperHandler->processNotifications()
04.09 10:09:57 [Server] Server thread/DEBUG #17 src/pocketmine/Server(2259): pocketmine\snooze\SleeperHandler->sleepUntil(double 1536055797.5863)
04.09 10:09:57 [Server] Server thread/DEBUG #18 src/pocketmine/Server(2134): pocketmine\Server->tickProcessor()
04.09 10:09:57 [Server] Server thread/DEBUG #19 src/pocketmine/Server(1700): pocketmine\Server->start()
04.09 10:09:57 [Server] Server thread/DEBUG #20 src/pocketmine/PocketMine(243): pocketmine\Server->__construct(BaseClassLoader object, pocketmine\utils\MainLogger object, string /, string /plugins/)
04.09 10:09:57 [Server] Server thread/DEBUG #21 /custom-php7.2.phar(1): require(string phar:///custom-php7.2.phar/src/pocketmine/PocketMine.php)