title: Typed property Spatie\Feed\FeedItem::$author must not be accessed before initialization
body: <p>I am using laravel spatie/laravel-feed for generate feed for my blog site</p>
  <p>here is the method for get all item</p>
  <pre><code>    public static function getFeedItems()
  {
     return Post::all();
  }
  </code></pre>
  <p>Here is the method for generate data</p>
  <pre><code>    public function toFeedItem(): FeedItem
  {
      return FeedItem::create([
          'id' =&gt; $this-&gt;id,
          'title' =&gt; $this-&gt;title,
          'summary' =&gt; $this-&gt;meta_description,
          'updated' =&gt; $this-&gt;updated_at,
          'link' =&gt; url('/', $this-&gt;slug),
          'authorName' =&gt; $this-&gt;title,
      ]);
  }
  </code></pre>
  <p>I have added this in my web.php</p>
  <pre><code>Route::feeds();
  </code></pre>
  <p>i have added the link in my view like this</p>
  <pre><code> @include('feed::links')
  </code></pre>
  <p>when i am visiting this link then it's showing this error</p>