PHPExcel breaks the page in wordpress

I’m trying to use the library PHPExcel inside wordpress.

I created a class to parse the csv file, but just call the method to read the file PHPExcel_IOFactory::load($file) or even to identify the file, page breaks.

The problem is that I do not get any results, only the blank page.

Not even on the apache log errors occur.

The class is this:

require('vendor/PHPExcel/Classes/PHPExcel/IOFactory.php');

class parseCsv {

    protected $file;
    protected $fileType;

    public function __construct($file)
    {
        $this->file = $file;
        $this->fileType = PHPExcel_IOFactory::identify($this->file);

    }

    public function parseCsv()
    {
        $objReader = PHPExcel_IOFactory::createReader($this->fileType);
        $objPHPExcel = $objReader->load($this->file);
        $objWorksheet = $objPHPExcel->getActiveSheet();
        foreach ($objWorksheet->getRowIterator() as $row) {
            $cellIterator = $row->getCellIterator();
            $cellIterator->setIterateOnlyExistingCells(false);
            foreach ($cellIterator as $cell) {
                $cell_value = $cell->getValue();
                var_dump($cell_value);
            }
        }
    }

} 

Definitely something wrong but I can not figure out where.

EDIT

Instantiate the class name in the file functions.php in wp-content/themes/myproject in this way:

function exec_at_init()
{
    ...
    require('helpers/parse/parse.php');
}
function create_regcontabilita()
{
    $parse = new parse('helpers/parse/matrice.csv');
    $parse->parseCsv();
}