Plugin can break queries that use custom post types

The plugin function blog_search_filter causes problems when using a WP_Query that contains a search term. The filter overrides the post_type field with any even when a WordPress search wasn’t made. This means searches that are narrowed to a custom post type will include everything.

Quick example (when the plugin is enabled):

// Create a query to find pages.
$my_query = new WP_Query(array(
    'post_type' => 'page',
    's'         => 'search term',
) );

// This will echo "any", but it should be "page".
echo $my_query->query_vars['post_type'];

One potential fix is to only override the post type when it’s set in the url:

// Replace lines 78-81 of "osd-blog-search-widget.php" with
// the following:
if ( $post_type ) {
    $query->set( 'post_type', $post_type );
}			

An alternative would be to include an additional hidden field on the form (like osd_blog_search or similar) and then only change the post type when that is set to true.

Thank you!