Reupload Problème Calendrier PHP

Bonjour, je fait un calendrier en PHP avec l'aide de la vidéo suivante :
https://www.youtube.com/watch?t=1896&v=qzE949YCYic&feature=youtu.be
(Je suis entre 33 min et 39 min)

J'obtiens cette erreur :



Quand je clique sur les détails de mes evenement:



Pouvez m'aider s'il vous plait

Mon Code est en Plusieurs Partie (Je n''est pas tout upload seulement le plus important )

index :

        <?php
use App\Date\Month;
use Calendar\Events;

        require_once('../src/bootstrap.php');
        require_once('../src/Calendar/Month.php');
        require_once('../src/Calendar/Events.php');
        
        $pdo = get_pdo();
        $events = new  Calendar\Events($pdo);
        $month = new Calendar\Month($_GET['month'] ?? null, $_GET['year'] ?? null);
        $start = $month->getStartingDay();
        $start = $start->format('N') === '1' ? $start : $month->getStartingDay() ->modify('last monday');
        $weeks = $month->getWeeks();
        $end = (clone $start)->modify('+'. (6 + 7 * ($weeks-1)) .' days');
        $events = $events->getEventsBetweenByDay($start, $end);
        require_once('../views/header.php');
        ?>

        <div class="d-flex flex-row align-items-center justify-content-between mx-sm-3">
        <h1><?= $month->toString(); ?></h1>
        <div>
            <a href="?month=<?= $month->previousMonth()->month; ?>&year=<?= $month->previousMonth()->year; ?>" class="btn btn-primary"><</a>
            <a href="?month=<?= $month->nextMonth()->month; ?>&year=<?= $month->nextMonth()->year; ?>" class="btn btn-primary">></a>
        </div>
        </div>

        <table class="calendar__table calendar__table--<?= $month->getWeeks(); ?>weeks">
            <?php for ($i = 0; $i < $month->getWeeks(); $i++) : ?>
                <tr>
                    <?php 
                    foreach($month->days as $k => $day): 
                        $date = (clone $start)->modify("+" . ($k + $i * 7). "days");
                        $eventsForDay = $events[$date->format("Y-m-d")] ?? [];
                    ?>
                    <td class="<?= $month->withinMonth($date) ? '' : 'calendar__othermonth'; ?>">
                        <?php if ($i === 0) : ?>
                            <div class="calendar__weekday"><?= $day; ?></div>
                        <?php endif; ?>
                        <div class="calendar__day"><?= $date->format('d'); ?></div>
                        <?php foreach ($eventsForDay as $event) : ?>
                            <div class="calendar__event">
                                <?= (new DateTime($event['start']))->format('H:i')?> - <a href="/calendrier/public/event.php?id=<?= $event['id']; ?>"><?= ($event['name']); ?></a>
                            </div>
                        <?php endforeach; ?>     
                    </td>
                    <?php endforeach; ?>
                </tr>
            <?php endfor; ?>     
        </table>
        <?php require_once('../views/footer.php'); ?>

----------------------------------------
event.php :

<?php
use App\Date\Month;
use Calendar\Events;
require_once('../src/bootstrap.php');
require_once('../src/Calendar/Events.php');
$pdo = get_pdo();
$events = new Calendar\Events($pdo);
if(!isset($_GET['id'])){
    header('location: /404.php');
}
try{
    
    $event = $events->find($_GET['id']);
}catch(\Exception $e){
    e404();
}
require_once('../views/header.php');
?>


<h1><?= ($event->getName()); ?></h1>
<ul>
<li>Date : <?= $event->getStart()->format('d/m/Y'); ?></li>
<li>Heure de début : <?= $event->getStart()->format('H:i'); ?></li>
<li>Heure de fin : <?= $event->getEnd()->format('H:i'); ?></li>
<li>Description :<br>
<?= H($event->getDescription()); ?>
</li>
</ul> 

<?php require_once('../views/footer.php'); ?>

-------------------------------------------

Events.php:

<?php 
namespace Calendar;

use PDO;

class Events {

    private $pdo;

    public function __construct(\PDO $pdo)
    {
        $this->pdo = $pdo;
    }

    /**
     * Récup les évenements entre deux dates
     * @param \DateTime $start
     * @param \DateTime $end
     * @return array
     */
    public function getEventsBetween(\DateTime $start, \DateTime $end): array{
        $sql = "SELECT * FROM events WHERE start BETWEEN '{$start->format('Y-m-d 00:00:00')}' AND '{$end->format('Y-m-d 23:59:59')}'" ;
        $statement = $this->pdo->query($sql);
        $results = $statement->fetchAll();
        return $results;
    }

    /**
     * Récup les évenements entre deux dates indexé par jour
     * @param \DateTime $start
     * @param \DateTime $end
     * @return array
     */
    public function getEventsBetweenByDay(\DateTime $start, \DateTime $end): array{
        $events = $this->getEventsBetween($start, $end);
        $days = [];
        foreach($events as $event){
            $date = explode(' ', $event['start'])[0];
            if(!isset($days[$date])){
                $days[$date] = [$event];
            }else{
                $days[$date][] = $event;
            }
        }
        return $days;
    }   
    
    /**
     * Récupére un évenement 
     * @param int $id
     * @return array
     * @throws \Exception
     */
    public function find (int $id): \Calendar\Event{ 
        require_once('Event.php');
        $statement = $this->pdo->query("SELECT * FROM events WHERE id = $id LIMIT 1");
        $statement->setFetchMode(\PDO::FETCH_CLASS, \Calendar\Event::class);
        $result = $statement->fetch();

        if($result === false){
            throw new \Exception('Aucun résultat a était trouvé');
        }
        $re = new \Calendar\Event($result['id'],$result['name'],$result['description'],$result['start'],$result['end']);
        return $re;
    }
}

Event.php

 <?php

namespace Calendar;

class Event {
    private $id;
    private $name;
    private $description;
    private $start;
    private $end;

    function __construct($id, $name, $description, $start, $end)
    {
        $this->$id=$id;
        $this->$name=$name;
        $this->$description=$description;
        $this->$start=$start;
        $this->$end=$end;
    }

    public function getId(): int{
        return $this->id;
    }

    public function getName(): string{
        return $this->name;
    }

    public function getDescription(): ?string{
        return $this->description;
    }

    public function getStart(): \DateTime{
        return new \DateTime($this->start);
    }

    public function getEnd(): \DateTime{
        return new \DateTime($this->end);
    }
}

?>

bootstrap.php :

 <?php
function e404(){
    require_once('../public/404.php');
    exit();
}

function dd($vars){
    foreach($vars as $var){
        echo "<pre>";
        print_r($var);
        echo "</pre>";
    }
} 
function get_pdo (): PDO{
    return new PDO('mysql:host=localhost;dbname=chat', 'root','', [
        PDO:: ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION,
        PDO:: ATTR_DEFAULT_FETCH_MODE => \PDO:: FETCH_ASSOC
    ]);
}

function h (?string $value): string{
    if($value == null){
        return '';
    }
    return htmlentities($value);
}

-------------------------
Month.php :

<?php
namespace Calendar;

class Month {
    public $days = ['Lundi', 'Mardi', 'Mercredi', 'Jeudi', 'Vendredi', 'Samedi', 'Dmanche'];
    
    private $months = ['Janvier', 'Février', 'Mars', 'Avril', 'Mai', 'Juin', 'Juillet', 'Aout', 'Septembre', 'Octobre', 'Novembre', 'Décembre'];
    public $month;
    public $year;

    /**
     * Month constructor. 
     * @param int $month Le mois compris entre 1 et 12
     * @param int $year l'année 
     * @throw \Exception
     */
    public function __construct(?int $month = null, ?int $year = null){
        if ($month === null || $month <1 || $month >12){
            $month = intval(date('m'));
        }
        if($year === null){
            $year = intval(date('Y'));
        }
        $this->month = $month;
        $this->year = $year;
    }

    /**
     * Renvoi le premier jour du mois
     * @return \DateTime
     */
    public function getStartingDay (): \DateTime{
        return new \DateTime("{$this->year}-{$this->month}-01");
    }

    /**
     * Retourne le mois en toute lettre
     * @return string 
     */
    public function toString(): string {
       return $this ->months[$this->month - 1] . ' ' . $this->year;
    }

    /**
     * Renvoi le nombre de semaine dans le mois
     * @return int
     */
    public function getWeeks(): int{
        $start = $this->getStartingDay();
        $end = (clone $start)->modify('+1 month -1 day');
        $weeks = intval($end->format('W')) - intval($start->format('W')) +1; 
        if ($weeks < 0){
            $weeks = intval($end->format('W'));
        }
        return $weeks;
    }

    /**
     * Le jour est dans le mois en cours ?
     * @param \DateTime $date
     * @return bool
     */
    public function withinMonth (\DateTime $date ): bool{
        return $this->getStartingDay()->format('Y-m') === $date->format('Y-m');
    }

    /**
     * Renvoi le mois suivant
     * @return Month
     */
    public function nextMonth(): Month {
        $month = $this->month + 1;
        $year = $this->year;
        if($month > 12){
            $month =1;
            $year += 1;
        }
        return new Month($month, $year);
    }

    /**
     * Renvoi le mois précédent
     * @return Month
     */
    public function previousMonth(): Month {
        $month = $this->month - 1;
        $year = $this->year;
        if($month < 1){
            $month =12;
            $year -= 1;
        }
        return new Month($month, $year);
    }
}

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