Fix for #13860

Undefined error when inserting an empty link in the RTE editor

(cherry picked from commit 6ce30fb561)

# Conflicts:
#	src/Umbraco.Web.UI.Client/src/common/services/tinymce.service.js

src/Umbraco.Web.UI.Client/src/common/services/tinymce.service.js

@@ -1253,7 +1253,7 @@ function tinyMceService($rootScope, $q, imageHelper, $locale, $http, $timeout, s
 
             // the href might be an external url, so check the value for an anchor/qs
             // href has the anchor re-appended later, hence the reset here to avoid duplicating the anchor
-            if (!target.anchor) {
+      if (!target.anchor && href) {
                 var urlParts = href.split(/(#|\?)/);
                 if (urlParts.length === 3) {
                     href = urlParts[0];