MDL-87626 core_search: Fix typo in input value check

Co-authored-by: Uli Wessmann

public/lib/templates/search_input_navbar.mustache

@@ -99,7 +99,7 @@ function(
     const submit = container.querySelector('[data-action="submit"]');
 
     submit.addEventListener('click', (e) => {
-        if (input.valUE === '') {
+        if (input.value === '') {
             e.preventDefault();
         }
     });