upload files not read

this code below needs to do an encapsulation, it generates an error in the sequence with other codes, could someone tell me where I can understand this clearly or can someone explain it to me

<?php

require './vendor/autoload.php';
require 'csv.php';

use Aspera\Spreadsheet\XLSX\Reader;
use \Aspera\Spreadsheet\XLSX;
if(isset($_FILES['arquivo'])){
  $novo_nome = __DIR__ . "/upload/" . $_FILES['arquivo']['name'];
  move_uploaded_file($_FILES['arquivo']['tmp_name'], $novo_nome);

  $reader = new Reader();
  $reader->open($novo_nome);
  foreach($reader as $row) {
    print_r($row);
  }
}
?>