Trying to get property 'event' of non-object (View: /usr/home/gernikaracing/Apps/timing/vendor/encore/laravel-admin/resources/views/grid/table.blade.php)

protected function grid()
    {
        $grid = new Grid(new Participant);

        $eventId = request()->route('event');
        $grid->model()
                ->where('event_id', $eventId)
                ->orderBy('number', 'asc');

        $grid->header(function ($query) {
            $event = $query->first()->event->name;
            return "<div style='background-color:#f7f7f7; font-size: 18px; text-align: center; padding: 7px 10px; margin-top: 0;'>$event</div>";
        });
        $grid->authorized(__('Authorized'))->editable()->sortable();
        $grid->number(__('Number'))->sortable();
        $grid->driver()->full_name(__('Driver'))->sortable();
        $grid->codriver()->full_name(__('Codriver'))->sortable();
        $grid->team()->name(__('Team'))->sortable();
        $grid->vehicle()->full_name(__('Vehicle'))->sortable();
        $grid->group()->name(__('Group'))->sortable();
        $grid->division()->name(__('Class'))->sortable();
        $grid->admin_user()->name(__('Author'))->sortable();
        $grid->updated_at(__('Updated at'))->sortable();

        $grid->disableCreateButton();
        $grid->disableFilter();
        $grid->disableActions();
        $grid->disableExport();
        $grid->disableRowSelector();

        return $grid;
    }