particle problem, crash...

Why crash?!?!?

Error: Call to undefined method pocketmine\event\player\PlayerInteractEvent::getLevel()
File: /tuchparticle.phar/src/TheMaks/Main
Line: 21
Type: E_ERROR

THIS CRASH WAS CAUSED BY A PLUGIN
BAD PLUGIN: ToPa v1

Code:
[12] $this->getLogger()->info("on...");
[13] $this->getServer()->getPluginManager()->registerEvents($this,$this);
[14] }
[15] public function onInteract(PlayerInteractEvent $event){
[16] $p = $event->getPlayer();
[17] if($p->getInventory()->getItemInHand()->getId() == 280){
[18] $scale =1;
[19] $pos = new Vector3($p->getX()+1,$p->getY()+1,$p->getZ());
[20] $particle = new HeartParticle($pos, $scale);
[21] $event->getLevel()->addParticle($particle);
[22] }
[23] }
[24] }

Maybe you're missing getPlayer... I don't know, just try if it's work

PHP:

$event->getPlayer()->getLevel()->addParticle($particle);

Very big thanks :3