src/de/steamwar/lobby/listener/PlayerSeatListener.java

@@ -111,8 +111,9 @@ public class PlayerSeatListener implements Listener {
     public void onEntityDismount(EntityDismountEvent event) {
         seats.remove(getSeatLocation(event.getDismounted().getLocation()));
 
-        if (event.getEntityType() != EntityType.ARROW)
+        if (event.getEntityType() != EntityType.ARROW || event.getEntityType() != EntityType.ENDER_PEARL) {
             return;
+        }
 
         event.getDismounted().remove();
     }

src/de/steamwar/lobby/listener/RabbitListener.java

@@ -42,6 +42,9 @@ public class RabbitListener implements Listener {
         World world = Bukkit.getWorlds().get(0);
         spreadRabbits(250, world);
         Bukkit.getScheduler().runTaskTimer(LobbySystem.getInstance(), () -> {
+            if(Bukkit.getOnlinePlayers().isEmpty()) {
+                return;
+            }
             Rabbit rabbit = world.getEntitiesByClass(Rabbit.class).iterator().next();
             world.spawn(rabbit.getLocation(), Firework.class, firework -> {
                 FireworkMeta meta = firework.getFireworkMeta();