Index: inc/user-content.php
===================================================================
--- inc/user-content.php	(revision 3265)
+++ inc/user-content.php	(working copy)
@@ -62,7 +62,9 @@
 	 */
 	public static function scripts_and_styles() {
 		if ( is_singular() ) {
-			if ( '0' != get_comments_number() || \DevHub\post_type_has_source_code() || wporg_is_handbook_post_type() ) {
+			$is_handbook_post_type = function_exists( 'wporg_is_handbook_post_type' ) ? wporg_is_handbook_post_type() : false;
+
+			if ( '0' != get_comments_number() || \DevHub\post_type_has_source_code() || $is_handbook_post_type ) {
 				wp_enqueue_script( 'wporg-developer-function-reference', get_template_directory_uri() . '/js/function-reference.js', array( 'jquery', 'syntaxhighlighter-core', 'syntaxhighlighter-brush-php' ), '20150319', true );
 				wp_enqueue_style( 'syntaxhighlighter-core' );
 				wp_enqueue_style( 'syntaxhighlighter-theme-default' );
Index: searchform.php
===================================================================
--- searchform.php	(revision 3265)
+++ searchform.php	(working copy)
@@ -34,7 +34,7 @@
 <?php } ?>
 
 	<?php
-		$is_handbook = wporg_is_handbook();
+		$is_handbook = function_exists( 'wporg_is_handbook' ) ? wporg_is_handbook() : false;
 		$search_url  = $is_handbook ? wporg_get_current_handbook_home_url() : home_url( '/' );
 		$form_class  = $is_handbook ? ' searchform-handbook' : '';
 	?>