Throwing Sword Call to a member function

Hello, i'm a newbie that trying to create a PMMP Pocketmine Plugin, but when i try to make this plugins, i recently get error message
Call to a member function getDataPropertyManager() on null"

and here is my code

PHP:

$aimPos = $ev->getPlayer()->getDirectionVector();
        $nbt = new CompoundTag("", [
            "Pos" => new ListTag("Pos", [
                new DoubleTag("", $ev->getPlayer()->x),
                new DoubleTag("", $ev->getPlayer()->y + $ev->getPlayer()->getEyeHeight()),
                new DoubleTag("", $ev->getPlayer()->z)
            ]),
            "Motion" => new ListTag("Motion", [
                new DoubleTag("", $aimPos->x),
                new DoubleTag("", $aimPos->y),
                new DoubleTag("", $aimPos->z)
            ]),
            "Rotation" => new ListTag("Rotation", [
                new FloatTag("", $ev->getPlayer()->yaw - 75),
                new FloatTag("", $ev->getPlayer()->pitch)
            ]),
            "Health" => new ShortTag("Health", 5),
            "Item" => new CompoundTag("Item", [
                "id" => new ShortTag("id", Item::DIAMOND_SWORD),
                "Damage" => new ShortTag("Damage", 0),
                "Count" => new ByteTag("Count", 1),
            ]),
            "PickupDelay" => new ShortTag("PickupDelay", 0x7F),
        ]);
//initEntity()
        $player = $ev->getPlayer();
        $sword = Entity::createEntity("SwordThrowTask", $ev->getPlayer()->getLevel(), $nbt, $ev->getPlayer());
        $sword->getDataPropertyManager()->setByte(Entity::DATA_ARMOR_STAND_POSE_INDEX, 8);
        $sword->setMotion($sword->getMotion()->multiply(1.5));
        $sword->spawnToAll();
        $player->getInventory()->setItemInHand(Item::get(Item::AIR));

 

If the entity you're trying to spawn isn't registered, Entity::createEntity will return null
https://github.com/pmmp/PocketMine-...cddf085/src/pocketmine/entity/Entity.php#L373

 

Can you fix my code ? Just fix the call member function error

 

What Entity are you trying to spawn? Why did you put "SwordThrowTask" there?

 

I wanted to spawn Armor Stand pose 8 but the armor stand is going invisible, then Holding a sword

 

SwordThrowTask is my Class , its at SwordThrowTask.php

 

But why did you put it in the createEntity method?

 

So it should be Item? or can you fix my code ? I told i'm newbje that trying to code

 

It's an armor stand, right? I don't think armor stands are registered in pmmp by default, you probably need to make your own ArmorStand class.