Call to unknown member function Chest::getInventory?

It happens when I choose a chest with getBlock(), how can I bypass or solve it?

A chest is a Tile.

Yeah, but how can I convert it to an inventory holder?

Do you read? A Chest is a tile, not a block(well, it is a block, but you need the tile). You get it? No?

PHP:

Level::getTile(Vector3 $pos);

I got it, how can I get then if a block is a tile or a block? :/

How about learning this(click)?

PHP:

if($chest instanceof Chest){ // Chest as a Tile, not the block.

}

So much lol
Why is there even an documentation for if?

So you think I dont know instanceof? That was not my question... Its already solved

You asked to know if a block is a tile or a block.
A block is a block, not a tile. A block can contain a tile, but itself isn't a tile. So you check if it contains a tile if getTile with it returns a tile, using instanceof (although you can actually use !==null as well).