fix(nav-bar): null check tabs when updating nav-bar (#9071)

Author: Sam Elliott De La Torre Babá

src/components/navBar/navBar.js

@@ -222,6 +222,11 @@ MdNavBarController.prototype._initTabs = function() {
 MdNavBarController.prototype._updateTabs = function(newValue, oldValue) {
   var self = this;
   var tabs = this._getTabs();
+
+  // this._getTabs can return null if nav-bar has not yet been initialized
+  if(!tabs)
+    return;
+
   var oldIndex = -1;
   var newIndex = -1;
   var newTab = this._getTabByName(newValue);
@@ -266,11 +271,12 @@ MdNavBarController.prototype._updateInkBarStyles = function(tab, newIndex, oldIn
  * @private
  */
 MdNavBarController.prototype._getTabs = function() {
-  var linkArray = Array.prototype.slice.call(
-      this._navBarEl.querySelectorAll('.md-nav-item'));
-  return linkArray.map(function(el) {
-    return angular.element(el).controller('mdNavItem');
-  });
+  var controllers = Array.prototype.slice.call(
+    this._navBarEl.querySelectorAll('.md-nav-item'))
+    .map(function(el) {
+      return angular.element(el).controller('mdNavItem')
+    });
+  return controllers.indexOf(undefined) ? controllers : null;
 };
 
 /**

src/components/navBar/navBar.spec.js

@@ -175,6 +175,17 @@ describe('mdNavBar', function() {
           expect(getTab('tab2').attr('ui-sref-opts'))
               .toBe('{"reload":true,"notify":true}');
         });
+
+    it('does not update tabs if tab controller is undefined', function() {
+      $scope.selectedTabRoute = 'tab1';
+
+      spyOn(Object.getPrototypeOf(ctrl), '_updateInkBarStyles');
+      spyOn(Object.getPrototypeOf(ctrl), '_getTabs').and.returnValue(null);
+      createTabs();
+
+      expect(ctrl._updateInkBarStyles)
+        .not.toHaveBeenCalled();
+    });
   });
 
   describe('inkbar', function() {