fix(typeahead): add guard for destroyed $scope

- Add guard against accessing $scope when it has been destroyed

Closes #5267

Author: kwiateusz

src/tooltip/tooltip.js

@@ -287,18 +287,20 @@ angular.module('ui.bootstrap.tooltip', ['ui.bootstrap.position', 'ui.bootstrap.s
 
               // First things first: we don't show it anymore.
               ttScope.$evalAsync(function() {
-                ttScope.isOpen = false;
-                assignIsOpen(false);
-                // And now we remove it from the DOM. However, if we have animation, we
-                // need to wait for it to expire beforehand.
-                // FIXME: this is a placeholder for a port of the transitions library.
-                // The fade transition in TWBS is 150ms.
-                if (ttScope.animation) {
-                  if (!transitionTimeout) {
-                    transitionTimeout = $timeout(removeTooltip, 150, false);
+                if(ttScope){
+                  ttScope.isOpen = false;
+                  assignIsOpen(false);
+                  // And now we remove it from the DOM. However, if we have animation, we
+                  // need to wait for it to expire beforehand.
+                  // FIXME: this is a placeholder for a port of the transitions library.
+                  // The fade transition in TWBS is 150ms.
+                  if (ttScope.animation) {
+                    if (!transitionTimeout) {
+                      transitionTimeout = $timeout(removeTooltip, 150, false);
+                    }
+                  } else {
+                    removeTooltip();
                   }
-                } else {
-                  removeTooltip();
                 }
               });
             }