这是代码，如果文件不是图像，我想停止后期发布。这可能吗？

case "window-image":
        $format = \'image\';
        $title = esc_html($_POST[\'title_image\']);
        $tags = $_POST[\'tags_image\'];
        $comments = isset($_POST[\'comments_image\']) ? 1 : 0;
        $anonymous = isset($_POST[\'anonymous_image\']) ? 1 : 0;
        $comment_status = $comments == 1 ? \'open\' : \'closed\';
        $user_id = $id;

        if(($_FILES[\'image_imagepost\'][\'error\'] != 0 && $image == \'\') || $title == \'\') {
            wp_redirect(home_url(\'/\') . \'?posterror=1\');
            exit; 
        }       

        $post = array(
          \'comment_status\' => $comment_status,
          \'ping_status\'    => \'open\',
          \'post_author\'    => $user_id,
          \'post_content\'   => \'\',
          \'post_status\'    => $status,
          \'post_title\'     => $title,
          \'post_type\'      => \'post\',
         );  
        $post_id = wp_insert_post($post);

#Create attachment
    if (!function_exists(\'wp_generate_attachment_metadata\')){
        require_once(ABSPATH . "wp-admin" . \'/includes/image.php\');
        require_once(ABSPATH . "wp-admin" . \'/includes/file.php\');
        require_once(ABSPATH . "wp-admin" . \'/includes/media.php\');
    }
        $upload = wp_upload_bits( $_FILES[\'file\'][\'name\'], null, file_get_contents( $_FILES[\'file\'][\'tmp_name\'] ) );
        $wp_filetype = wp_check_filetype( basename( $upload[\'file\'] ), null );
        $wp_upload_dir = wp_upload_dir();
        $attachment = array(
            \'guid\' => $wp_upload_dir[\'baseurl\'] . _wp_relative_upload_path( $upload[\'file\'] ),
            \'post_mime_type\' => $wp_filetype[\'type\'],
            \'post_title\' => preg_replace(\'/\\.[^.]+$/\', \'\', basename( $upload[\'file\'] )),    
            \'post_content\' => \'\',
            \'post_author\' => $user_id,
            \'post_status\' => \'inherit\'
        );
        $attach_id = wp_insert_attachment( $attachment, $upload[\'file\'], $post_id );
        require_once(ABSPATH . \'wp-admin/includes/image.php\');
        $attach_data = wp_generate_attachment_metadata( $attach_id, $upload[\'file\'] );
        wp_update_attachment_metadata( $attach_id, $attach_data );
#Create attachment

#Use attachment
        update_post_meta( $post_id, \'_thumbnail_id\', $attach_id );
#Use attachment


        $nsfw = isset($_POST[\'nsfw_image\']) ? 1 : 2;
        add_post_meta($post_id, \'_standard_nsfw\', $nsfw);
        add_post_meta($post_id, \'_anonymous\', $anonymous);

        break;