Fix possible dupe glitch

Author: dries-c

src/muqsit/invmenu/InvMenuEventHandler.php

@@ -4,6 +4,7 @@
 
 namespace muqsit\invmenu;
 
+use muqsit\invmenu\inventory\InvMenuInventory;
 use muqsit\invmenu\session\network\PlayerNetwork;
 use muqsit\invmenu\session\PlayerManager;
 use pocketmine\event\inventory\InventoryCloseEvent;
@@ -62,6 +63,12 @@ public function onInventoryTransaction(InventoryTransactionEvent $event) : void{
 		$player_instance = $this->player_manager->get($player);
 		$current = $player_instance->getCurrent();
 		if($current === null){
+			foreach($transaction->getActions() as $action){
+				if($action instanceof SlotChangeAction && $action->getInventory() instanceof InvMenuInventory){
+				    $event->cancel();
+				    return;
+				}
+			}
 			return;
 		}