Don't crash the linkpicker if only an anchor has been entered

(cherry picked from commit 1089b4b9bb)

src/Umbraco.Web.UI.Client/src/views/common/infiniteeditors/linkpicker/linkpicker.controller.js

@@ -93,7 +93,7 @@ angular.module("umbraco").controller("Umbraco.Editors.LinkPickerController",
                     });
 
                 }
-            } else if ($scope.model.target.url.length) {
+            } else if ($scope.model.target.url && $scope.model.target.url.length) {
                 // a url but no id/udi indicates an external link - trim the url to remove the anchor/qs
                 // only do the substring if there's a # or a ?
                 var indexOfAnchor = $scope.model.target.url.search(/(#|\?)/);