Warning: Illegal string offset ‘singular_name’ in class-post-type.php:215

I encountered this warning:
llegal string offset ‘singular_name’ in \wp-content\plugins\wpfront-user-role-editor\includes\post-type\class-post-type.php:215

I looked to see why this was happening.
To do so, I looked at what $this->post_type_args[$post_type] looks like.
This is what I got:

array (
  'label' => 'Vc Templates',
  'public' => false,
  'publicly_queryable' => false,
  'exclude_from_search' => false,
  'show_ui' => false,
  'show_in_menu' => false,
  'menu_position' => 10,
  'menu_icon' => 'dashicons-admin-page',
  'hierarchical' => false,
  'taxonomies' => 
  array (
  ),
  'has_archive' => false,
  'rewrite' => false,
  'query_var' => false,
  'show_in_nav_menus' => false,
)

This post type is registered by the WPBakery Pagebuilder.

This appears to be the same data passed to the register_post_type function in /plugins/js_composer/include/classes/core/shared-templates/class-vc-shared-templates.php:150ff

Since the “labels” key is optional and so is its descendant “singular_name”, PHP has to create new entries and that seems to cause the warning.

I have changed the function as follows:

/**
         * Fetches the singular name after registration if it does not exist. WP does not supply it as part of the arguments.
         * 
         * @param type $post_type
         * * @param type $post_type_object
         * @return type
         */
        public function registered_post_type($post_type, $post_type_object) {
            if (empty($this->post_type_args[$post_type])) {
                return;
            }

            if (!empty($this->post_type_args[$post_type]['labels']['singular_name'])) {
                return;
            }
            else{
              $this->post_type_args[$post_type] = ['labels' => ['singular_name' => $post_type_object->labels->singular_name]];
            }

Now the warning is gone and everything runs smoothly on my development system.
However, since my change would be overwritten in the next update of your plugin, I would like to ask you to check the problem and use the code I provided if necessary.

Kind regards

Alexander Behling