Throw exception when an invalid chunk is set as the parent of a Tile/Entity

src/pocketmine/entity/Entity.php

@@ -147,6 +147,10 @@ abstract class Entity extends Position implements Metadatable{
 
 
 	public function __construct(Chunk $chunk, Compound $nbt){
+		if($chunk->getLevel() === null){
+			throw new \Exception("Invalid garbage Chunk given to Entity");
+		}
+
 		$this->id = Entity::$entityCount++;
 		$this->justCreated = true;
 		$this->namedtag = $nbt;

src/pocketmine/tile/Tile.php

@@ -27,6 +27,7 @@ namespace pocketmine\tile;
 
 use pocketmine\event\Timings;
 use pocketmine\level\format\Chunk;
+use pocketmine\level\format\LevelProvider;
 use pocketmine\level\Position;
 use pocketmine\nbt\tag\Compound;
 
@@ -62,6 +63,10 @@ abstract class Tile extends Position{
 	public $tickTimer;
 
 	public function __construct(Chunk $chunk, Compound $nbt){
+		if($chunk->getLevel() === null){
+			throw new \Exception("Invalid garbage Chunk given to Tile");
+		}
+
 		$this->server = $chunk->getLevel()->getLevel()->getServer();
 		$this->chunk = $chunk;
 		$this->setLevel($chunk->getLevel()->getLevel(), true); //Strong reference