Fix 1.18 world reset

Signed-off-by: Lixfel <agga-games@gmx.de>

FightSystem_Core/src/de/steamwar/fightsystem/fight/FightWorld.java

@@ -29,9 +29,12 @@ import de.steamwar.fightsystem.utils.FlatteningWrapper;
 import org.bukkit.Bukkit;
 import org.bukkit.World;
 import org.bukkit.WorldCreator;
+import org.bukkit.entity.Entity;
 import org.bukkit.entity.EntityType;
 import org.bukkit.entity.Player;
 
+import java.util.ArrayList;
+import java.util.List;
 import java.util.Objects;
 
 public class FightWorld extends StateDependent {
@@ -65,10 +68,13 @@ public class FightWorld extends StateDependent {
     }
 
     public static void resetWorld(){
+        List<Entity> entities = new ArrayList<>();
         Recording.iterateOverEntities(Objects::nonNull, entity -> {
             if(entity.getType() != EntityType.PLAYER && (!Config.ArenaLeaveable || Config.ArenaRegion.inRegion(entity.getLocation())))
-                entity.remove();
+                entities.add(entity);
         });
+        entities.forEach(Entity::remove);
+        entities.clear();
 
         World backup = new WorldCreator(Config.world.getName() + "/backup").createWorld();
         assert backup != null;