Illegal string offset Warning in Wordpress

[admin]

I am facing error/Warning Illegal string offset

I have check all my code but no error reason found.
with below function my theme style is working the code is written in word press theme in the function.php.

<blockquote>
( ! ) SCREAM: Error suppression ignored for
( ! ) Warning: Illegal string offset 'face' in F:\wamp\www\wordpress-3.6.1-newsduke\wp-content\themes\hotnews\functions\theme-functions.php on line 140
</blockquote>

 function freshthemes_theme_styles() {

        /* Google fonts array */
        $google_fonts = array_keys( freshthemes_typography_get_google_fonts() );

        /* Define all the options that possibly have a unique Google font */
        $body_font = ft_get_option('body_font', 'Arial, Helvetica, san-serif');
        $heading_font = ft_get_option('heading_font', 'Arial, Helvetica, san-serif');
        $menu_nav_font = ft_get_option('menu_nav_font', 'Arial, Helvetica, san-serif');

        /* Get the font face for each option and put it in an array */
        $selected_fonts = array(
            $body_font['face'],
            $heading_font['face'],
            $menu_nav_font['face'],
        );

        /* Remove any duplicates in the list */
        $selected_fonts = array_unique($selected_fonts);

        /* If it is a Google font, go ahead and call the function to enqueue it */
        foreach ( $selected_fonts as $font ) {
            if ( in_array( $font, $google_fonts ) ) {
                freshthemes_typography_enqueue_google_font($font);
            }
        }

        // Register our styles.
        wp_register_style('main', get_stylesheet_uri(), false, THEME_VERSION, 'all');
        wp_register_style('prettyPhoto', THEME_DIR . '/stylesheets/prettyPhoto.css', false, THEME_VERSION, 'all');
        wp_register_style('responsive', THEME_DIR . '/stylesheets/responsive.css', false, THEME_VERSION, 'all');
        wp_register_style('custom-style', THEME_DIR . '/functions/framework/frontend/custom-style.css', false, filemtime(THEME_PATH . '/functions/framework/frontend/custom-style.css'), 'all');

        // Enqueue them.
        wp_enqueue_style('main');
        wp_enqueue_style('custom-style');
        wp_enqueue_style('prettyPhoto');
        wp_enqueue_style('responsive');
    }