after i click on Save&Close i receive error

defined('_JEXEC') or die('Restricted Access');

use Joomla\CMS\Factory;
use Joomla\CMS\Language\Text;
use Joomla\CMS\MVC\View\HtmlView;
use Joomla\CMS\Toolbar\ToolbarHelper;
use Joomla\CMS\Helper\ContentHelper;

class AvisamusicdbViewMusic extends HtmlView
{
    protected $item;
    protected $form;

    public function display($tpl = null)
    {
        $this->item = $this->get('Item');
        $this->form = $this->get('Form');

        if (count($errors = $this->get('Errors'))) {
            throw new \Exception(implode('<br>', $errors), 500);
        }

        $this->addToolbar();

        return parent::display($tpl);
    }

    protected function addToolbar()
    {
        $input = Factory::getApplication()->input;
        $input->set('hidemainmenu', true);

        $user = Factory::getUser();
        $userId = $user->id;
        $isNew = $this->item->id == 0;
        $canDo = ContentHelper::getActions('com_avisamusicdb', 'component');

        ToolbarHelper::title(sprintf('%s: %s', Text::_('COM_AVISAMUSICDB'), Text::_('COM_AVISAMUSICDB_TITLE_MUSICS_EDIT')), '');

        if ($canDo->get('core.edit')) {
            ToolbarHelper::apply('music.apply', 'JTOOLBAR_APPLY');
            ToolbarHelper::save('music.save', 'JTOOLBAR_SAVE');
            ToolbarHelper::save2new('music.save2new');
            ToolbarHelper::save2copy('music.save2copy');
        }

        ToolbarHelper::cancel('music.cancel', 'JTOOLBAR_CLOSE');
    }
}

what wrong here ?