Unable to reverse value for property path […]: The choice […] does not exist or is not unique

This value is not valid.

Unable to reverse value for property path "author":
 The choice "9" does not exist or is not unique.

use SymfonyComponentFormExtensionCoreChoiceListChoiceList;
use SymfonyComponentFormExtensionCoreChoiceListLazyChoiceList;

class StaffChoiceList extends LazyChoiceList
{
    public function __construct($staffService, $loginStaff)
    {
        $this->staffService = $staffService;
        $this->loginStaff = $loginStaff;
    }

    public function setCurrentStaff($currentStaff)
    {
        $this->currentStaff = $currentStaff;
    }

    public function loadChoiceList($value = null)
    {
        // Get the same shop staff as the login staff
        $staffs = $this->staffService->getStaffByShop($this->loginStaff->getShop());

        If the current staff is not included in the acquired staff (due to transfer etc.), add it to the end
        if ($this->currentStaff && !array_search($this->currentStaff, $staffs)) {
            $staffs[] = $this->currentStaff;
        }
            return new ChoiceList($staffs, $staffs);
    }
}

use SymfonyComponentFormChoiceListLoaderChoiceLoaderInterface;
use SymfonyComponentFormChoicelistArrayChoiceList;

class StaffChoiceLoader implements ChoiceLoaderInterface
{
    public function loadChoiceList($value = null)
    {
        $staffs = $this->staffService->getStaffByShop($this->loginStaff->getShop());

        if ($this->currentStaff && !array_search($this->currentStaff, $staffs)) {
            $staffs[] = $this->currentStaff;
        }
            return new arrayChoiceList($staffs, null);
    }
    public function loadChoicesForValues(array $values, $value = null)
    {
        // Optimized when no data is preset
        if (empty($choices))
        {
            return array();
        }

        $values = array();
        foreach ($choices as $choice)
        {
            $values[] = (string) $this->loginStaff->getId();
        }

        return $values;
    }

    public function loadValuesForChoices(array $choices, $value = null)
    {
        // Optimized when nothing is sent
        if (empty($values))
        {
            return array();
        }

        // Get the entity from the ID and return the required data
        return $this->staffService->getStaffByShop($this->loginStaff->getShop());
    }
}

        $authorChoiceList = new StaffChoiceLoader($this->staffService, $options['login_staff']);
        $builder->add("author", EntityType::class, array(
            "required" => true,
            "class" => "AppBundle:Staff",
            "choice_loader" => $authorChoiceList,
            "choice_label" =>function ($value) {
              return $value;
            },
        ));
        $builder->addEventListener(FormEvents::PRE_SET_DATA, function (FormEvent $event) use ($authorChoiceList) {
            $article = $event->getData();
            $authorChoiceList->setCurrentStaff($article->getAuthor());
        });
    public function configureOptions(OptionsResolver $resolver)
    {
        $resolver->setDefaults(array(
            "validation_groups" => function (FormInterface $form) {
                $article = $form->getData();
                return $this->getValidationGroups($article->getArticleStatus());
            },
        ));
    }

    /**
     * __toString
     *
     * @return string
     */
    public function __toString()
    {
        return $this->staffName;
    }
    /**
     * Set staffName
     *
     * @param string $staffName
     * @return Staff
     */
    public function setStaffName($staffName)
    {
        $this->staffName = $staffName;

        return $this;
    }

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

    /**
     * @ORMManyToOne(targetEntity="Staff")
     * @ORMJoinColumn(name="author_id", referencedColumnName="id", nullable=true)
     */
    protected $author;
    /**
     * Set author
     *
     * @param AppBundleModelEntityStaff $author
     * @return Article
     */
    public function setAuthor(AppBundleModelEntityStaff $author = null)
    {
        $this->author = $author;

        return $this;
    }

    /**
     * Get author
     *
     * @return AppBundleModelEntityStaff
     */
    public function getAuthor()
    {
        return $this->author;
    }

    public function __construct($staffService, array $options = [])
    {
        $this->staffService = $staffService;
        $this->loginStaff = $options['login_staff'];
        $this->currentStaff = $options['login_staff'];
    }

Notice: Undefined index: login_staff

use SymfonyComponentFormExtensionCoreTypeChoiceType;
use AppEntityStaff;

class StaffType extends AbstractType
{
    public function __construct($staffService)
    {
        $this->staffService = $staffService;
    }

    public function buildForm(FormBuilderInterface $builder, array $options): void
    {
        $currentStaff = $options['currentStaff'];
        $loginStaff = $options['loginStaff'];
    
        $staff = $this->staffService->getStaffByShop($loginStaff->getShop());
        // If the current staff is not included in the acquired staff (due to transfer etc.), add it to the end
        if ($currentStaff && !array_search($currentStaff, $staffs)) {
            $staff[] = $currentStaff;
        }
    
        $builder->add('author', ChoiceType::class, [
            'choices' => $staffs,
            'choice_label' => function(Staff $employee, $key) {
                return $employee->getName();
            }
        ]);
    }
}

$staff = [
    1 => new Staff(1),
    2 => new Staff(2),
    3 => new Staff(3),  
];

$options = [
    'currentStaff' => $currentStaff,
    'loginStaff' => $loginStaff,
];
$this->createForm(StaffType::class, $data, $options);