Invalid argument supplied for foreach

[aitorserra]

Hello!

When I added the code to a new mu-plugin for allow guest voting, I'm getting this error the first time the user visit the website:

Warning: Invalid argument supplied for foreach() in /home/username/public_html/wp-content/plugins/comment-popularity/inc/class-comment-popularity.php on line 363

After the user vote, this error is removed. What can I do to fix it for new users? It doesn't give a good impression to show an error.

Thank you.