Solved Why does registerEvent cause an Error?

Hey, i coded a plugin but every time i start it, it says:
pocketmine\plugin\PluginManager::registerEvent(): Argument #1 ($event) must be of type string
Here is the code:

Code:

    public function onEnable(): void
    {
        $this->getLogger()->getInfo("ForeverCMD is activated!");
        $this->getServer()->getPluginManager()->registerEvent($this, $this);
        @mkdir($this->getDataFolder());
        $this->saveDefaultConfig();
        $this->getResource("config.yml");
    }

 

registerEvents

 

Ah, didn't coded for some time so