Crashhh

[AGTHARN]

My server crashed and this crash dump was generated, please help me with it thanks

PocketMine-MP Crash Dump Sat Apr 18 13:47:05 WEST 2020

Error: Call to a member function isClosed() on null
File: plugins/BurgerSpawners (1).phar/src/Heisenburger69/BurgerSpawners/EventListener
Line: 74
Type: Error

THIS CRASH WAS CAUSED BY A PLUGIN
BAD PLUGIN: BurgerSpawners v0.1.0

Code:
[65]
[66] /**
[67] * @param EntitySpawnEvent $event
[68] */
[69] public function onSpawn(EntitySpawnEvent $event): void
[70] {
[71] $entity = $event->getEntity();
[72] $this->plugin->getScheduler()->scheduleDelayedTask(new ClosureTask(function (int $currentTick) use ($entity): void {
[73] if (in_array($entity->getId(), $this->plugin->exemptedEntities)) return;
[74] if($entity->getLevel()->isClosed()) return;
[75] $disabledWorlds = ConfigManager::getArray("mob-stacking-disabled-worlds");
[76] if (is_array($disabledWorlds)) {
[77] if (in_array($entity->getLevel()->getFolderName(), $disabledWorlds)) {
[78] return;
[79] }
[80] }
[81]
[82] if (ConfigManager::getToggle("allow-mob-stacking")) {
[83] if ($entity instanceof Human or !$entity instanceof Living) return;
[84] $mobStacker = new Mobstacker($entity);

Backtrace:
#0 src/pocketmine/scheduler/ClosureTask(61): Heisenburger69\BurgerSpawners\EventListener->Heisenburger69\BurgerSpawners{closure}(integer 134686)
#1 src/pocketmine/scheduler/TaskHandler(134): pocketmine\scheduler\ClosureTask->onRun(integer 134686)
#2 src/pocketmine/scheduler/TaskScheduler(176): pocketmine\scheduler\TaskHandler->run(integer 134686)
#3 src/pocketmine/plugin/PluginManager(643): pocketmine\scheduler\TaskScheduler->mainThreadHeartbeat(integer 134686)
#4 src/pocketmine/Server(2380): pocketmine\plugin\PluginManager->tickSchedulers(integer 134686)
#5 src/pocketmine/Server(2143): pocketmine\Server->tick()
#6 src/pocketmine/Server(1990): pocketmine\Server->tickProcessor()
#7 src/pocketmine/Server(1584): pocketmine\Server->start()
#8 src/pocketmine/PocketMine(273): pocketmine\Server->__construct(object BaseClassLoader, object pocketmine\utils\MainLogger, string[26] /home/minecraft-pe/server/, string[34] /home/minecraft-pe/server/plugins/)
#9 src/pocketmine/PocketMine(296): pocketmine\server()
#10 (11): require(string[81] phar:///home/minecraft-pe/server/PocketMine-MP.phar/src/pocketmine/PocketMine.ph)

[AGTHARN]

Thank you