Ticket #45903: 45903.patch

src/wp-content/themes/twentynineteen/js/priority-menu.js

@@ -116 +116 @@
                 }
 
                 // Adds the necessary UI to operate the menu.
-                var visibleList  = container.parentNode.querySelector('.main-menu[id]');
-                var hiddenList   = visibleList.parentNode.nextElementSibling.querySelector('.hidden-links');
-                var toggleButton = visibleList.parentNode.nextElementSibling.querySelector('.main-menu-more-toggle');
+                var visibleList        = container.parentNode.querySelector('.main-menu[id]');
+                var nextElementSibling = visibleList.parentNode.nextElementSibling;
 
+                if ( ! nextElementSibling ) {
+                        return;
+                }
+
+                var hiddenList   = nextElementSibling.querySelector('.hidden-links');
+                var toggleButton = nextElementSibling.querySelector('.main-menu-more-toggle');
+
                 if ( isOverflowingNavivation( visibleList, toggleButton, container ) ) {
 
                         // Record the width of the list

src/wp-content/themes/twentynineteen/js/touch-keyboard-navigation.js

@@ -279 +279 @@
                                 // Remove Focused elements in sibling div
                                 var currentDiv        = getCurrentParent( event.target, 'div', '.main-navigation' );
                                 var currentDivSibling = currentDiv.previousElementSibling === null ? currentDiv.nextElementSibling : currentDiv.previousElementSibling;
+
+                                if ( ! currentDivSibling ) {
+                                        return;
+                                }
+
                                 var focusedElement    = currentDivSibling.querySelector( '.is-focused' );
                                 var focusedClass      = 'is-focused';
                                 var prevLi            = getCurrentParent( event.target, '.main-navigation > div > ul > li', '.main-navigation' ).previousElementSibling;