I am not using this plugin but came across a similar error on my own custom autoset featured image, which I have modified from here.
I have included a few extra lines which means you don’t get the debug errors on posts that haven’t been created yet e.g. on new-post.php and new-page.php admin screens
The following may help you:
Create a new file called and name it something like featured-image.php and save somewhere in your themes folder
Then include a reference to if from your functions.php file e.g. (replace /inc/ with your path to the file)
require get_template_directory() . '/inc/featured-image.php';
Then in the featured-image.php file drop the following code
/**
* Autoset featured image to first image in post if not specifically defined
*/
add_action('the_post', 'your_theme_autoset_featured_image');
add_action('save_post', 'your_theme_autoset_featured_image');
add_action('draft_to_publish', 'your_theme_autoset_featured_image');
add_action('new_to_publish', 'your_theme_autoset_featured_image');
add_action('pending_to_publish', 'your_theme_autoset_featured_image');
add_action('future_to_publish', 'your_theme_autoset_featured_image');
function your_theme_autoset_featured_image() {
//checks for thumbnail - it does not use the global post ID because we haven't created a post yet!
if ( !has_post_thumbnail() ){
// if post does not have a thumbnail then do nothing!!
}
else {
// set globals for the function
global $post;
$already_has_thumb = has_post_thumbnail($post->ID);
$screen = get_current_screen();
/*
* checks that you are not on add a new post or add new page screen, so it is not looking for empty objects and thus returning no debug errors! Yay!
*/
// check for thumb and what admin page you are on
if (!$already_has_thumb && $screen->base !== '-new.php') {
$attached_image = get_children( "post_parent=$post->ID&post_type=attachment&post_mime_type=image&numberposts=1" );
if ($attached_image) {
foreach ($attached_image as $attachment_id => $attachment) {
set_post_thumbnail($post->ID, $attachment_id);
}
}
}
}
}
The crucial bits in the code above are
if ( !has_post_thumbnail() ){
// if post does not have a thumbnail then do nothing!!
}
and
if (!$already_has_thumb && $screen->base !== '-new.php') {
//original code
}
You might be able to modify the plugin php files with the extra bits Hope this helps
