Hello everyone. New to the forum and with very little knowledge about coding, I am trying to resolve a warning that appeared in a plugin that I use for my website. I first posted this in the General PHP help section, only to realise a few days later that this forum had a dedicated Wordpress section which is more suitable for my question. I guess only administrators can move posts, so this is a re-post.
About two weeks ago, I had to restore my entire Wordpress site from a backup after a core update failed, and the error I am trying to resolve appeared afterwards. While I was at it, I updated the site’s php version to 8.0.11, so I’m not sure if that is the culprit.
On my website, I use a plugin called Circles Gallery to display images in more or less every post. I use the free version of the plugin, since the limited configuration options are more than enough for my needs. However, the plugin doesn’t seem to be updated or supported anymore, which of course could also be a factor in this warning popping up.
Anyhoo, if you go to any post where the gallery is used (e.g. http://thegreatoceanliners.com/articles/great-eastern) you will see the following warning at the top:
Warning: Undefined array key “prettyphoto_theme” in /storage/content/77/168877/thegreatoceanliners.com/public_html/wp-content/plugins/circles-gallery/public/class-circles-gallery.php on line 137 Warning: Undefined array key “colorbox_theme” in /storage/content/77/168877/thegreatoceanliners.com/public_html/wp-content/plugins/circles-gallery/public/class-circles-gallery.php on line 138
The gallery itself works just as intended, though, with all the images lined up as circles in a single column to the right. After some searching, it seems that I can just edit the wp-config file in order to hide the warning, but I would prefer to eliminate the problem that causes the warnings in the first place. The only trouble is that I don’t know enough about PHP to understand or rectify the code. 
The php file that the warning refers to can be accessed here, and more specifically the array looks like this:
extract(shortcode_atts(array(
‘gallery_width’ => $defaults[‘gallery_width’],
‘circle_width’ => $defaults[‘circle_width’],
‘circle_max_width’ => $defaults[‘circle_max_width’],
‘columns_no’ => $defaults[‘columns_no’],
‘columns_no_1024’ => $defaults[‘columns_no_1024’],
‘columns_no_768’ => $defaults[‘columns_no_768’],
‘columns_no_phone’ => $defaults[‘columns_no_phone’],
‘circle_background_color’=> $defaults[‘circle_background_color’],
‘hover_effect’ => $defaults[‘hover_effect’],
‘title_font_size’ => $defaults[‘title_font_size’],
‘title_color’ => $defaults[‘title_color’],
‘description_font_size’ => $defaults[‘description_font_size’],
‘description_color’ => $defaults[‘description_color’],
‘circle_border_size’ => $defaults[‘circle_border_size’],
‘circle_border_color’ => $defaults[‘circle_border_color’],
‘margin_bottom’ => $defaults[‘margin_bottom’],
‘text_position’ => $defaults[‘text_position’],
‘circle_icon’ => $defaults[‘circle_icon’],
‘circle_icon_color’ => $defaults[‘circle_icon_color’],
‘item_height’ => $defaults[‘item_height’],
‘custom_css’ => $defaults[‘custom_css’],
‘click_action’ => $defaults[‘click_action’],
‘prettyphoto_theme’ => $defaults[‘prettyphoto_theme’],
‘colorbox_theme’ => $defaults[‘colorbox_theme’],
‘ids’ => ‘’
), $atts));
Lines 137 and 138 are the ones about ‘prettyphoto_theme’ and ‘colorbox_theme’ respectively. These two variables are locked in the free version and can’t be changed (see attached screenshot), so my guess is that this is also a factor.
So, can anyone help? Is there some snippet of code that I can add to circumvent this warning? Again, the gallery itself works fine otherwise, so the warning doesn’t appear to be anything critical. Just annoying, and I would like to sort it out instead of just hiding it. 
Thanks in advance for any feedback!