Fixed an error occurring if doing a "PageFinder::getQuery" and the current user has no language field.

This can occur in the following case :
1 - calling wire("session")->login,
2 - getting a page in the sites pages,
3 - redirecting to this page.

If the logged-in user has no defined language field, there is a php error during step 2 (like: calling "isDefault() on a non object).