Fix an annoying quest NPE

Plugins/Nautilus.Game.Arcade/src/nautilus/game/arcade/quest/QuestTracker.java

@@ -1,5 +1,9 @@
 package nautilus.game.arcade.quest;
 
+import java.util.Arrays;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
 import org.bukkit.entity.Player;
 import org.bukkit.event.Listener;
 
@@ -63,7 +67,7 @@ public class QuestTracker<T extends Game> implements Listener
 					boolean cont = true;
 					for (String questItem : quest.getItem())
 					{
-						for (String str : items)
+						for (String str : Arrays.stream(items).filter(Objects::nonNull).collect(Collectors.toList()))
 						{
 							String first = str.replaceAll(" ", "");
 							String compare = questItem.replaceAll(" ", "");