Why is libraries-override not removing assets?

Question

My attempt to remove CSS and JS assets is not working. I have placed the following declarations in my module's *.info.yml file. But after clearing the cache, I still see the assets in the head of the document. Is there anything wrong with my syntax:

libraries-override:
  global-styling:
    css:
      base:
        /themes/stack/css/lightbox.min.css: false
    js:
      /themes/stack/js/lightbox.min.js: false

Here is the relevant Drupal documentation: https://www.drupal.org/docs/8/theming/adding-stylesheets-css-and-javascript-js-to-a-drupal-8-theme#override-extend

I also tried these for the key:

• stack/global-styling
• stack.global-styling

I also tried it without the full paths:

libraries-override:
  stack/global-styling:
    css:
      base:
        lightbox.min.css: false
    js:
      lightbox.min.js: false

Nothing is working so far.

Answer 1

This doesn't answer the original question, but turns out to be a better solution in my case. You must clear your cache with each change to this function:

/**
 * Implements hook_library_info_alter().
 */
function example_library_info_alter(&$libraries, $extension) {

  // If you have 'stack' as your subtheme, you might have unwanted lightbox assets.
  if ('stack' === $extension) {

    if (isset($libraries['global-styling'])) {

      $current_path = \Drupal::service('path.current')->getPath();
      $path_args = explode('/', $current_path);

      // Your conditions may vary.
      if ('book' == $path_args[1] && isset($path_args[2]) && is_numeric($path_args[2])) {

        // Helper function below.
        if (example_array_key_exists_r('css/lightbox.min.css', $libraries)) {
            unset($libraries['global-styling']['css']['base']['css/lightbox.min.css']);
        }

        if (example_array_key_exists_r('js/lightbox.min.js', $libraries)) {
            unset($libraries['global-styling']['js']['js/lightbox.min.js']);
        }

      }
    }
  }

}

/**
 * Recursively search for an array key.
 *
 * @see https://stackoverflow.com/a/2948985/861826
 *
 */
function example_array_key_exists_r($needle, $haystack) {

  $result = array_key_exists($needle, $haystack);

  if ($result) return $result;

    foreach ($haystack as $v) {
      if (is_array($v)) {
        $result = example_array_key_exists_r($needle, $v);
      }
      if ($result) return $result;
    }

    return $result;
}