problem Undefined array key "id" in livewie calander laravel

Question

iam using livewire calander from this website https://www.tutsmake.com/laravel-livewire-fullcalendar-integration-example/ when iam drag and drop one event from date and set it in anther calander date it appear this error Undefined array key "id" in livewie calander in this code

public function eventDrop($event, $oldEvent)
{
    $eventdata = Event::find($event['id']);
    $eventdata->start = $event['start'];
    $eventdata->save();
}