MultiLanguage plugin help me to finish it

hello

i am working on a multi language plugin but there is 1 error and i cannot find the problem

error:

Spoiler

PHP:

Notice: Undefined property: Mcrafters\MultiLanguage\Main::$data in /Users/Ronny/Desktop/v20/plugins/MultiLanguage-master/src/Mcrafters/MultiLanguage/Main.php on line 44
[07:02:39] [Server thread/CRITICAL]: "Could not pass event 'pocketmine\event\player\PlayerJoinEvent' to 'Test v1': Call to a member function get() on null on MCrafterss\test
[07:02:39] [Server thread/CRITICAL]: Error: "Call to a member function get() on null" (EXCEPTION) in "/MultiLanguage-master/src/Mcrafters/MultiLanguage/Main" at line 44

github page: https://github.com/BoxOfDevs/MultiLanguage

Did you delete the event on line 44 ?
Also are you missed the Case sensitive ?

PHP:

$this->data = new Config($this->getDataFolder()."Data.yml", Config::YAML, array());
$this->saveResource("data.yml"); // Right here

Also, where's your Data.yml file in your Resource folder ?

line 43

Why set/get something in Config with null ?
The $player is Player, not Player's Name

PHP:

public function onJoin(PlayerJoinEvent $event){
        $event->getPlayer()->sendMessage(ML::getInstance()->Translate($event->getPlayer()->getName(), "testmessage"));
    }

Also you shouldn't use PlayerJoinEvent, use PlayerLoginEvent.
And get the Player's name in the function, not in the sendMessage.

PHP:

public function Translate(Player $player, $message, bool $force = false, $issuer = "none") : int{
                $player = $player->getName();
        if ($this->getPlayerLang($player) === "nl"){
            $this->NL->get($message);
        }
        if ($this->getPlayerLang($player) === "en"){
            $this->EN->get($message);
        }
        if ($this->getPlayerLang($player) === "fr"){
            $this->FR->get($message);
        }
        if ($this->getPlayerLang($player)=== "de"){
            $this->DE->get($message);
        }
    }

Notice: Undefined property: pocketmine\event\player\PlayerJoinEvent::$getPlayer in /Users/Ronny/Desktop/v20/plugins/testplugin/src/Mcrafterss/test.php on line 18
[07:00:24] [Server thread/CRITICAL]: "Could not pass event 'pocketmine\event\player\PlayerJoinEvent' to 'Test v1': Call to a member function sendMessage() on null on MCrafterss\test
[07:00:24] [Server thread/CRITICAL]: Error: "Call to a member function sendMessage() on null" (EXCEPTION) in "/testplugin/src/Mcrafterss/test" at line 18

Oh yea sorry, check the code in edited post