Issue #3310145 by nikathone: Fix...

    if ($library_id) {

      $old_key = 'charts_default_settings.' . $library_id . '_settings';

      $library_config = $config->get($old_key);

      $config->set('library_config', $library_config);

      $config->set('charts_default_settings.library_config', $library_config);

      $config->clear($old_key);

      $config->save();

    }

  }

}

/**

 * Clear library_config set on the wrong place. See drupal.org/i/3310145.

 */

function charts_post_update_clear_library_config_key_added_on_wrong_place(&$sandbox) {

  /** @var \Drupal\Core\Config\ConfigFactoryInterface $config_factory */

  $config_factory = \Drupal::service('config.factory');

  $config = $config_factory->getEditable('charts.settings');

  if ($config && $config->get('library_config')) {

    // Not to be confused with "charts_default_settings.library_config" which is

    // the proper key.

    $config->clear('library_config');

    $config->save();

  }

}