SkinImage: throw on wrong data length

src/pocketmine/network/mcpe/protocol/types/SkinImage.php

@@ -34,6 +34,9 @@ class SkinImage{
 	private $data;
 
 	public function __construct(int $height, int $width, string $data){
+		if(($expected = $height * $width * 4) !== ($actual = strlen($data))){
+			throw new \InvalidArgumentException("Data should be exactly $expected bytes, got $actual bytes");
+		}
 		$this->height = $height;
 		$this->width = $width;
 		$this->data = $data;