PHP注意：在制作symfony表单模板时，“数组到字符串转换”

I'm following A symfony tutorial in the official documentation. However When I get to Field Type Options symfony throws the error "An exception has been thrown during the rendering of a template ("Notice: Array to string conversion") in form_div_layout.html.twig at line 13."

I have checked on google and typos, the offending line, from the documentation seems to be:

->add('dueDate', DateType::class, array('widget' => 'single_text'))

Which is straight from the documentation. For context the rest of the file looks like this:

<?php

namespace AppBundle\Controller;

use AppBundle\Entity\Task;

use Symfony\Component\Form\Extension\Core\Type\TextType;
use Symfony\Component\Form\Extension\Core\Type\DateType;
use Symfony\Component\Form\Extension\Core\Type\SubmitType;

use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
use Symfony\Component\HttpFoundation\Request;

class DefaultController extends Controller
{
    /**
     * @Route("/", name="homepage")
     */
    public function indexAction(Request $request)
    {
        // replace this example code with whatever you need
        return $this->render('default/index.html.twig', [
            'base_dir' => realpath($this->getParameter('kernel.root_dir').'/..'),
        ]);
    }

    /**
     * @Route("/form", name="formmma")
     */
    public function newAction(Request $request)
    {
        // create a task and give it some dummy data for this example
        $task = new Task();
        $task->setTask('Write a blog post');

        $task->setDueDate(new \DateTime('tomorrow'));

        $form = $this->createFormBuilder($task)
            ->add('task', TextType::class)
           // ->add('dueDate', DateType::class)
            ->add('dueDate', DateType::class, array('widget' => 'single_text'))
           // ->add('dueDate', null, array(
           //     'widget' => 'single_text',
           //     'required' => false
           // ))

            ->add('save', SubmitType::class, array('label' => 'Create Task'))
            ->getForm();

        $form->handleRequest($request);

        if ($form->isSubmitted() && $form->isValid()) {
             // ... perform some action, such as saving the task to the database

             return $this->redirectToRoute('task_success');
        }

        return $this->render('default/new.html.twig', array(
            'form' => $form->createView(),
        ));
    }
}

in your controller put

     if ($form->isSubmitted()) {
        $dateFrom=$booking->dateOfArrival;
        $booking->dateOfArrival= new \DateTime();
        $booking->dateOfArrival->setDate($dateFrom->format('Y'),$dateFrom->format('m'),$dateFrom->format('d'));}

PS: "booking" is the model used in the form