The required option "em" is missing.

Address.php

<?php

namespace AppBundle\Entity;

use Doctrine\ORM\Mapping as ORM;

/**
 * Address
 *
 * @ORM\Table(name="address")
 * @ORM\Entity(repositoryClass="AppBundle\Repository\AddressRepository")
 * @ORM\HasLifecycleCallbacks
 */
class Address {

    /**
     * @var int
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @var string
     *
     * @ORM\Column(name="country", type="string", length=255, nullable=true)
     */
    private $country;

    /**
     * @var string
     *
     * @ORM\Column(name="state", type="string", length=255, nullable=true)
     */
    private $state;

    /**
     * @var string
     *
     * @ORM\Column(name="city", type="string", length=255, nullable=true)
     */
    private $city;

    /**
     * @var string
     *
     * @ORM\Column(name="street", type="text")
     */
    private $street;

    /**
     * @var string
     *
     * @ORM\Column(name="token", type="string", length=255, unique=true, nullable=true)
     */
    private $token;

    /**
     * @var \DateTime
     *
     * @ORM\Column(name="created_at", type="datetime")
     */
    private $createdAt;

    /**
     * @var \DateTime
     *
     * @ORM\Column(name="updated_at", type="datetime", nullable=true)
     */
    private $updatedAt;

    /**
     * Get id
     *
     * @return integer 
     */
    public function getId() {
        return $this->id;
    }

    /**
     * Set country
     *
     * @param string $country
     * @return Address
     */
    public function setCountry($country) {
        $this->country = $country;

        return $this;
    }

    /**
     * Get country
     *
     * @return string 
     */
    public function getCountry() {
        return $this->country;
    }

    /**
     * Set street
     *
     * @param string $street
     * @return Address
     */
    public function setStreet($street) {
        $this->street = $street;

        return $this;
    }

    /**
     * Get street
     *
     * @return string 
     */
    public function getStreet() {
        return $this->street;
    }

    /**
     * Set state
     *
     * @param string $state
     * @return Address
     */
    public function setState($state) {
        $this->state = $state;

        return $this;
    }

    /**
     * Get state
     *
     * @return string 
     */
    public function getState() {
        return $this->state;
    }

    /**
     * Set city
     *
     * @param string $city
     * @return Address
     */
    public function setCity($city) {
        $this->city = $city;

        return $this;
    }

    /**
     * Get city
     *
     * @return string 
     */
    public function getCity() {
        return $this->city;
    }

    /**
     * Set token
     *
     * @param string $token
     * @return Address
     */
    public function setToken($token) {
        $this->token = $token;

        return $this;
    }

    /**
     * Get token
     *
     * @return string 
     */
    public function getToken() {
        return $this->token;
    }

    /**
     * Set createdAt
     *
     * @param \DateTime $createdAt
     * @return Address
     */
    public function setCreatedAt($createdAt) {
        $this->createdAt = $createdAt;

        return $this;
    }

    /**
     * Get createdAt
     *
     * @return \DateTime 
     */
    public function getCreatedAt() {
        return $this->createdAt;
    }

    /**
     * Set updatedAt
     *
     * @param \DateTime $updatedAt
     * @return Address
     */
    public function setUpdatedAt($updatedAt) {
        $this->updatedAt = $updatedAt;

        return $this;
    }

    /**
     * Get updatedAt
     *
     * @return \DateTime 
     */
    public function getUpdatedAt() {
        return $this->updatedAt;
    }
}

AddressType.php

<?php

class AddressType extends AbstractType {

    private $em;

    public function __construct($em) {
        $this->em = $em;
    }

    /**
     * @param FormBuilderInterface $builder
     * @param array $options
     */
    public function buildForm(FormBuilderInterface $builder, array $options) {

        // cela suppose que le gestionnaire d'entité a été passé en option
        $entityManager = $options['em'];
        $propertyPathToCity = 'city';

        $builder
                ->add('street')
        ;
        $builder
                ->addEventSubscriber(new AddCountryFieldSubscriber($propertyPathToCity, $this->em, $builder->getFormFactory()))
                ->addEventSubscriber(new AddStateFieldSubscriber($propertyPathToCity, $this->em, $builder->getFormFactory()))
                ->addEventSubscriber(new AddCityFieldSubscriber($propertyPathToCity, $this->em, $builder->getFormFactory()))
        ;
    }

    /**
     * @param OptionsResolver $resolver
     */
    public function configureOptions(OptionsResolver $resolver) {
        $resolver->setDefaults(array(
            'data_class' => 'AppBundle\Entity\Address'
        ));
        $resolver->setRequired(array(
            'em',
        ));
        $resolver->setAllowedTypes('em', 'Doctrine\Common\Persistence\ObjectManager');
    }

}

CandidateType.php

<?php

class CandidateType extends AbstractType {

    protected $em;

    public function __construct($em) {
        $this->em = $em;
    }

    /**
     * @param FormBuilderInterface $builder
     * @param array $options
     */
    public function buildForm(FormBuilderInterface $builder, array $options) {
        $builder
                ->add('firstName')
                ->add('lastName')
                ->add('address', new AddressType($this->em))
        ;
    }

    /**
     * @param OptionsResolver $resolver
     */
    public function configureOptions(OptionsResolver $resolver) {
        $resolver->setDefaults(array(
            'data_class' => 'AppBundle\Entity\Candidate'
        ));
        $resolver->setRequired(array(
            'em',
        ));
        $resolver->setAllowedTypes('em', 'Doctrine\Common\Persistence\ObjectManager');
    }

}

Controller.php

<?php

class JobSeekerController extends Controller {

public function editProfileAction(Request $request, Account $account) {
        $candidate = $account->getCandidate();
        $em = $this->getDoctrine()->getManager();
        $editCandidate = $this->createForm(new \AppBundle\Form\CandidateType($em), $candidate, array(
            'em' => $this->getDoctrine()->getManager()
        ));
  }
}