Undefined array key: 'symbol'

[kylescousin]

I have this really simple Mega filter to allow toggling of column visibility: But when loading the page it says: undefined array key "symbol"

It gives that for all table columns, except for "Name" - What could be the reason for this?

<?php

namespace App\Nova;

use Carbon\Carbon;

use Illuminate\Http\Request;
use Laravel\Nova\Fields\ID;
use Laravel\Nova\Fields\Text;
use DigitalCreative\MegaFilter\MegaFilter;
use Laravel\Nova\Http\Requests\NovaRequest;
use DigitalCreative\MegaFilter\HasMegaFilterTrait;
use DigitalCreative\MegaFilter\Column;
class Post extends Resource
{
    use HasMegaFilterTrait;

    public static $model = \App\Models\Post::class;
    public static $title = 'symbol';
    public static $tableStyle = 'tight';
    public static $showColumnBorders = true;

    public static $search = ['id',
        'symbol',
        'name',
    ];

    /**
     * Get the fields displayed by the resource.
     *
     * @param \Illuminate\Http\Request $request
     * @return array
     */
    public function fields(Request $request)
    {
        return [
            Text::make('Name')->sortable(),
            Text::make('Symbol')->sortable(),

        ];
    }

    /**
     * Get the cards available for the request.
     *
     * @param \Illuminate\Http\Request $request
     * @return array
     */
    public function cards(Request $request)
    {
        return [
            MegaFilter::make([
                'columns' => [
                    Column::make('Name', 'name'),
                    Column::make('Symbol', 'symbol'),
                ]
            ])
        ];
    }

    /**
     * Get the filters available for the resource.
     *
     * @param \Illuminate\Http\Request $request
     * @return array
     */
    public function filters(Request $request)
    {
        return [];
    }

    /**
     * Get the lenses available for the resource.
     *
     * @param \Illuminate\Http\Request $request
     * @return array
     */
    public function lenses(Request $request)
    {
        return [];
    }

    /**
     * Get the actions available for the resource.
     *
     * @param \Illuminate\Http\Request $request
     * @return array
     */
    public function actions(Request $request)
    {
        return [];
    }
}