Infinite looping next post link within a certain category on a post

based on the docu:

• the $in_same_term parameter in https://developer.wordpress.org/reference/functions/next_post_link/
• the categories’ parameters in WP_Query https://developer.wordpress.org/reference/classes/wp_query/#category-parameters
• and how to get a post’s category https://developer.wordpress.org/reference/functions/get_the_category/
• and in collaboration with @zackwww;

‘infinitely looping ‘next post’ link at the bottom of a post that only links to posts in that category’

if( get_adjacent_post(true, '', false, 'category') ) {
   next_post_link($format="%link", $link = 'Next Article', $in_same_term = true, $taxonomy = 'category'); 
} else { 
   $thiscat = get_the_category(); 
   $catslug = $thiscat[0]->slug; 
   $last = new WP_Query( array( 
      'posts_per_page' => 1, 
      'order' => 'ASC', 
      'category_name' => $catslug  
    ) ); 
   $last->the_post(); 
   echo '<a href="' . get_permalink() . '">Next Article</a>'; 
   wp_reset_postdata(); 
}