Server thread/CRITICAL Error: "Call to a member function get() on null" (EXCEPTION) in "plugins/Mine

I have some problems with using the config.yml. Its all set up but it is crashing all time i try the command. onCommand the plugin is looking if the "editor" is equal with "unset"(Here could be a gamertag or something else too.) And on this point it kicks me out of the server.

PHP:

class main extends PluginBase implements Listener{
    public $cfg;

    public function onLoad() : void{
        $this->getLogger()->info(TextFormat::WHITE . "I've been loaded!");
    }

    public function onEnable() : void{
if(!is_dir($this->getDataFolder())){
    @mkdir($this->getDataFolder());
}
$this->saveResource("config.yml");
if(!file_exists($this->getDataFolder()."config.yml")){
    $this->cfg = new Config($this->getDataFolder()."config.yml", Config::YAML);
if(!$this->cfg->get("editor")){
        $this->cfg->set("editor", "unset");
        }
}

$this->getServer()->getPluginManager()->registerEvents($this, $this);
        $this->getLogger()->info(TextFormat::DARK_GREEN . "I've been enabled!");
    }

    public function onDisable() : void{
        $this->getLogger()->info(TextFormat::DARK_RED . "I've been disabled!");
    }

public function onCommand(CommandSender $sender, Command $command, string $label, array $args) : bool{
        if(strtolower($command->getName()) === "mf"){

if($args[0] == "create"){
$p = $sender->getPlayer();
$editor = $this->cfg->get("editor");
if($this->cfg->get($this->cfg->get("editor")) == "unset"){
$this->cfg->set("editor", $p->getName());
}else{
$sender->sendMessage("Another player is using the editor!");
}
}
}
}
}

 

Remove this line
if(!file_exists($this->getDataFolder()."config.yml"))