Fix incorrect SQL select

Now in my file i18n_menu.module on the end of file a have this code

/**
 * Load menu item by path, language
 */
function i18n_menu_link_load($path, $langcode) {
  $query = db_select('menu_links', 'ml');
  $query->leftJoin('menu_router', 'm', 'm.path = ml.router_path');
  $query->fields('ml');
  // Weight should be taken from {menu_links}, not {menu_router}.
  $query->addField('ml', 'weight', 'link_weight');
  $query->fields('m');
  $query->condition('ml.link_path', $path);
  $query->condition('ml.language', $langcode);
  $query->condition('m.path', 'IS NOT NULL'); // <--- fix here
  if ($item = $query->execute()->fetchAssoc()) {
    $item['weight'] = $item['link_weight'];
    _menu_link_translate($item);
    return $item;
  }
}

What is the problem?

If you add more than one language (in my case 4: English, French, German and Russian), and by default not English, there is a problem switching to a language which is set as the default language.

When selecting from the database returns a string, from which eventually formed the wrong URL, which is required in reality.

For example, when I'm on the home page, activate the English version of the site - I'm staying on the main page, with English translation of an activated interface. If I try to change to another language, except for the default language - everything will be fine (although to be honest - a stress test were not satisfied). And if I want to switch to the default language does not get home, and some or the other (usually the 1st page of the menu).