Check world before checking distance. Fixes BUKKIT-1792

src/main/java/org/bukkit/craftbukkit/CraftWorld.java

@@ -763,6 +763,9 @@ public class CraftWorld implements World {
     }
 
     public void playEffect(Location location, Effect effect, int data, int radius) {
+        Validate.notNull(location, "Location cannot be null");
+        Validate.notNull(effect, "Effect cannot be null");
+        Validate.notNull(location.getWorld(), "World cannot be null");
         int packetData = effect.getId();
         Packet61WorldEvent packet = new Packet61WorldEvent(packetData, location.getBlockX(), location.getBlockY(), location.getBlockZ(), data);
         int distance;
@@ -770,6 +773,7 @@ public class CraftWorld implements World {
 
         for (Player player : getPlayers()) {
             if (((CraftPlayer) player).getHandle().netServerHandler == null) continue;
+            if (!location.getWorld().equals(player.getWorld())) continue;
 
             distance = (int) player.getLocation().distanceSquared(location);
             if (distance <= radius) {