Add better error message for missing files / improper library install

Had to debug slick.install to figure out what was going on - I had created /sites/libraries/slick and uploaded lib files, but was still getting an error about not having Slick installed properly.

slick.install looks for the slick.min.js file specifically.

Please consider providing better requirements messages for slightly easier troubleshooting!

/**
 * Implements hook_requirements().
 *
 * Checks for the Slick library.
 */
function slick_requirements($phase) {
  $t = get_t();
  $requirements = array();

  // Check for the Slick library.
  if ($phase == 'runtime') {
    $path = libraries_get_path('slick');
    if (!file_exists("{$path}/slick/slick.min.js")) {
      $requirements['slick_library'] = array(
        'description' => $t('Please ensure <a href="@url">slick.min.js</a> is present at [libraries-path]/slick.', array('@url' => 'https://github.com/kenwheeler/slick/')),
        'severity' => REQUIREMENT_ERROR,
        'value' => $t('Missing minified script.'),
        'title' => $t('Slick library'),
      );
    }
    if (!$path) {
      $requirements['slick_library'] = array(
        'description' => $t('The <a href="@url">Slick library</a> should be installed at [libraries-path]/slick.', array('@url' => 'https://github.com/kenwheeler/slick/')),
        'severity' => REQUIREMENT_ERROR,
        'value' => $t('Not installed.'),
        'title' => $t('Slick library'),
      );
    }

    // Check for the minimum required jQuery version.
    $jquery_version = variable_get('jquery_update_jquery_version', '1.5');
    if (!version_compare($jquery_version, '1.7', '>=')) {
      $requirements['slick_jquery_version'] = array(
        'description' => $t('Incorrect jQuery version detected. Slick requires jQuery 1.7 or higher. Please change your <a href="!settings">jQuery Update settings</a>.', array('!settings' => url('admin/config/development/jquery_update'))),
        'severity' => REQUIREMENT_ERROR,
        'value' => $t('Not installed. Please enable jQuery 1.7 or higher.'),
        'title' => $t('Slick jQuery version'),
      );
    }
  }

  return $requirements;
}