ObjectHydrator issue with OneToMany relationship

namespace Lms\Entities;
/**
 *
 * @Entity
 * @Table(name="User")
 */
class User {

	public function __constructor() {
		$social_media_links = new \Doctrine\Common\Collections\ArrayCollection;
	}
	/**
	 * @Id
	 * @Column(type="bigint")
	 * @GeneratedValue
	 */
	protected $id;

	/** @Column(type="string", nullable=TRUE, length=1024) */
	protected $mission_statement;

	/** @Column(type="string") */
	protected $first_name;

	/** @Column(type="string") */
	protected $last_name;

	/** @Column(type="string", nullable=TRUE, length=8) */
	protected $initial;

	/** @Column(type="string", nullable=TRUE) */
	protected $email;

	/** @Column(type="string", nullable=TRUE) */
	protected $company;

	/** @Column(type="string", nullable=TRUE, length=1024) */
	protected $picture;

	/** @Column(type="text", nullable=TRUE) */
	protected $bio;

	// unidirectional one to many relationship with social media link
	/**
	 * @ManyToMany(targetEntity="SocialMediaLink")
	 * @JoinTable(name="Users_Socialmedialinks",
	 *      joinColumns={@JoinColumn(name="user_id", referencedColumnName="id")},
	 *      inverseJoinColumns={@JoinColumn(name="socialmedialink_id", referencedColumnName="id", unique=true)}
	 *      )
	 */
	protected $social_media_links;
	

    /**
     * Add social_media_links
     *
     * @param SocialMediaLink $socialMediaLinks
     */
    public function addSocialMediaLinks(\SocialMediaLink $socialMediaLinks)
    {
        $this->social_media_links[] = $socialMediaLinks;
    }

    /**
     * Get social_media_links
     *
     * @return Doctrine\Common\Collections\Collection $socialMediaLinks
     */
    public function getSocialMediaLinks()
    {
        return $this->social_media_links;
    }
}

namespace Lms\Entities;

/**
 *
 * @Entity
 * @Table(name="SocialMediaLink")
 */
class SocialMediaLink {

	/**
	 * @Id
	 * @Column(type="bigint")
	 * @GeneratedValue
	 */
	protected $id;

	/** @Column(type="string") */
	protected $title;

	/** @Column(type="string") */
	protected $link;

}

		$sml = $this->_em->createQuery("SELECT s FROM Lms\Entities\User u JOIN u.social_media_links  AS s WHERE u.id = ?1 AND s.id = ?2")
					->setParameter(1, 1)
					->setParameter(2, 1)
					->getResult();

1) DoctrineExtensions\PHPUnit\UserTestCase::testEditSocialMediaLink
class_parents(): object or string expected

C:\xampp\htdocs\lms-user-sml-feature\system\application\libraries\Doctrine\ORM\Mapping\ClassMetadataFactory.php:201
C:\xampp\htdocs\lms-user-sml-feature\system\application\libraries\Doctrine\ORM\Mapping\ClassMetadataFactory.php:224
C:\xampp\htdocs\lms-user-sml-feature\system\application\libraries\Doctrine\ORM\Mapping\ClassMetadataFactory.php:148
C:\xampp\htdocs\lms-user-sml-feature\system\application\libraries\Doctrine\ORM\EntityManager.php:235
C:\xampp\htdocs\lms-user-sml-feature\system\application\libraries\Doctrine\ORM\Internal\Hydration\ObjectHydrator.php:220
C:\xampp\htdocs\lms-user-sml-feature\system\application\libraries\Doctrine\ORM\Internal\Hydration\ObjectHydrator.php:75
C:\xampp\htdocs\lms-user-sml-feature\system\application\libraries\Doctrine\ORM\Internal\Hydration\AbstractHydrator.php:98
C:\xampp\htdocs\lms-user-sml-feature\system\application\libraries\Doctrine\ORM\AbstractQuery.php:530
C:\xampp\htdocs\lms-user-sml-feature\system\application\libraries\Doctrine\ORM\AbstractQuery.php:360

<?xml version="1.0" encoding="UTF-8"?>
<dataset>
	<table name="user">
		<column>id</column>
		<column>mission_Statement</column>
		<column>first_name</column>
		<column>last_name</column>
		<column>initial</column>
		<column>email</column>
		<column>company</column>
		<column>picture</column>
		<column>bio</column>
		
		<row>
			<value>1</value>
			<value>Mission Statement 1</value>
			<value>First Name 1</value>
			<value>Last Name 1</value>
			<value>IN1</value>
			<value>email1@email.com</value>
			<value>Company 1</value>
			<value>Picture 1</value>
			<value>Bio 1</value>
		</row>
	</table>
	
	<table name="socialmedialink">
		<column>id</column>
		<column>title</column>
		<column>link</column>

		<row>
			<value>1</value>
			<value>Social Media Title 1</value>
			<value>Social Media Link 1</value>
		</row>
	</table>
	
	<table name="users_socialmedialinks">
		<column>user_id</column>
		<column>socialmedialink_id</column>

		<row>
			<value>1</value>
			<value>1</value>
		</row>
	</table>
</dataset>