instagram_importer-8.x-1.1/modules/instagram_importer_gallery/instagram_importer_gallery.install

<?php
/**
 * Implements hook_requirements()
 */
function instagram_importer_gallery_requirements() {
  $requirements = [];

  if (!file_exists('libraries/instagram-importer-gallery/jquery.instagram-importer-gallery.js') || !file_exists('libraries/photoswipe/dist/photoswipe.js')) {
    $requirements = [
      'instagram_importer_gallery.gallery' => [
        'title' => t('Instagram importer gallery'),
        'value' => t('Instagram importer gallery or photoswipe library missing'),
        'description' => t("See the readme.md file of the module or the project page for instructions."),
        'severity' => REQUIREMENT_WARNING,
      ],
    ];
  }

  return $requirements;
}