help in the console I get an error on line 112 but I don't know why

Here is the complete error code but the main one is line 112

public function onQuit(PlayerQuitEvent $event) {

$player = $event->getPlayer();
$player->getArmorInventory()->clearAll();
$player->setAllowFlight(false);
$player->setGamemode($this->getServer()->getDefaultGamemode());
$player->getInventory()->clearAll();
unset($this->removenpcmode[$player->getName()]);

if($player->getLevel()->getFolderName() == $this->getConfig()->get("arena")) {
unset($this->players[$player->getName()]);
}



That is the code and the error that marks me is this
$player->getInventory()->clearAll();
unset($this->removenpcmode[$player->getName()]);

 

What error?

 

maybe youre unsetting from not existing array