Arkadaşlar ben istiyorum ki resim bulunmayan bütün yazılara tek bir resmi thumbnail olarak eklesin. Kullandığım temada kodlara baktığımda bunun olması gerekiyor ama olmuyor

Functions`da bulunan kodlar:

////////////////////////////////////////////////////////////////////////////////
// get featured images
////////////////////////////////////////////////////////////////////////////////
if( !function_exists( 'get_featured_post_image' )):
function get_featured_post_image($before,$after,$width,$height,$class,$size,$alt,$title,$default) { //$size - full, large, medium, thumbnail
global $blog_id,$wpdb, $post, $posts;
$image_id = get_post_thumbnail_id();
$image_url = wp_get_attachment_image_src($image_id,$size);
$image_url = $image_url[0];
$current_theme = wp_get_theme();

$first_img = '';
ob_start();
ob_end_clean();
$output = preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $post->post_content, $matches);

if( isset($matches[1][0] ) ):
$first_img = $matches[1][0];
endif;

if( has_post_thumbnail( $post->ID ) ) {

return $before . "<img width='" . $width . "' height='". $height . "' class='" . $class . "' src='" . $image_url . "' alt='" . $alt . "' title='" . $title . "' />" . $after;

} else {

if($first_img) {
return $before . "<img width='" . $width . "' height='". $height . "' class='" . $class . "' src='" . $first_img . "' alt='" . $alt . "' title='" . $title . "' />" . $after;
} else {

if($default == 'true'):
return $before . "<img width='" . $width . "' height='". $height . "' class='" . $class . "' src='" . get_template_directory_uri() . '/images/post-default.jpg' . "' alt='" . $alt . "' title='" . $title . "' />" . $after;
endif;

}

}

}
endif;




////////////////////////////////////////////////////////////////////////////////
// get featured images
////////////////////////////////////////////////////////////////////////////////
if( !function_exists( 'get_featured_post_image_src' )):
function get_featured_post_image_src($before,$after,$size,$default) { //$size - full, large, medium, thumbnail
global $blog_id,$wpdb, $post, $posts;
$image_id = get_post_thumbnail_id();
$image_url = wp_get_attachment_image_src($image_id,$size);
$image_url = $image_url[0];

$first_img = '';
ob_start();
ob_end_clean();
$output = preg_match_all('/<img.+src=[\'"]([^\'"]+)[\'"].*>/i', $post->post_content, $matches);

if( isset($matches[1][0] ) ):
$first_img = $matches[1][0];
endif;

if( has_post_thumbnail( $post->ID ) ) {

return $before  . $image_url . $after;

} else {

if($first_img) {
return $before . $first_img . $after;
} else {

if($default == 'true'):
return $before  . get_template_directory_uri() . '/images/post-default.jpg' . $after;
endif;

}

}

}
endif;


if( !function_exists( 'get_post_id_outside_loop' )):

İndex`de bulunan kod:

////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////

<?php echo get_featured_post_image("<div class='post-thumb'>".$thepostlink, "</a></div>", 100, 100, "alignnone", 'thumbnail', mp_get_image_alt_text(),the_title_attribute('echo=0'), false); ?>

////////////////////////////////////////////////////////////////////////////////
////////////////////////////////////////////////////////////////////////////////

arkadaşlar 3 gündür sorunu çözemedim lütfen yardımcı olun.