I am working on a blogging application in Laravel 8.

The ArticlesController controller I have this method to display a single article, with comments:

namespace App\Http\Controllers;
use Illuminate\Http\Request;
use App\Models\User;
use App\Models\ArticleCategory;
use App\Models\Article;
use App\Models\Comment;

class ArticlesController extends FrontendController {

	// More code

	public function show($slug) {
		// Single article
		$article = Article::firstWhere('slug', $slug);
		$comments = Comment::where('article_id', $article->id)->orderBy('id', 'desc');
		return view('themes/' . $this->theme_directory . '/templates/single', 
			array_merge($this->data, [
				'categories' => $this->article_categories,
				'article' => $article,
				'comments' => $comments,
				'tagline' => $article->title,
				])
			);
	}
	
}

The problem

The problem is that the folowing piece of code intended to display the article comments throws an Parameter must be an array or an object that implements Countable error:

@if ($comments)
<h3>{{ count($comments) }} comments</h3>
<!-- START commentlist -->
<ol class="commentlist">
	@foreach ($comments as $comment)
	<li class="depth-1 comment">
		<div class="comment__avatar">
			<img class="avatar" src="{{ asset('images/avatars/' . $comment->user->avatar) }}" alt="" width="50" height="50">
		</div>
		<div class="comment__content">
			<div class="comment__info">
				<div class="comment__author">{{ $comment->user->first_name }} {{ $comment->user->last_name }}</div>
				<div class="comment__meta">
					<div class="comment__time">{{ date('jS M Y', strtotime($comment->created_at)) }}</div>
					<div class="comment__reply">
						<a class="comment-reply-link" href="#0">Reply</a>
					</div>
				</div>
			</div>
			<div class="comment__text">
				<p>{{ $comment->body }}</p>
			</div>
		</div>
	</li>
	@endforeach
</ol>

Questions

1. What causes this bug?
2. What is the easiest fix?