Make sure the nav item has children before trying to get them

+ Added LICENSE file
+ Renamed the KnowledgeBase demo module

LICENSE

@@ -0,0 +1 @@
+https://themeforest.net/licenses/terms/regular

src/app/core/components/navigation/navigation.service.ts

@@ -179,7 +179,10 @@ export class FuseNavigationService
 
             if ( navItem.type === 'collapse' || navItem.type === 'group' )
             {
-                this.getFlatNavigation(navItem.children);
+                if ( navItem.children )
+                {
+                    this.getFlatNavigation(navItem.children);
+                }
             }
         }
 

src/app/main/content/pages/knowledge-base/knowledge-base.module.ts

@@ -31,6 +31,6 @@ const routes = [
         FuseKnowledgeBaseArticleComponent
     ]
 })
-export class FuseKnowledgeBaseModule
+export class KnowledgeBaseModule
 {
 }

src/app/main/content/pages/pages.module.ts

@@ -20,7 +20,7 @@ import { PricingModule } from './pricing/pricing.module';
 import { ProfileModule } from './profile/profile.module';
 import { SearchModule } from './search/search.module';
 import { FaqModule } from './faq/faq.module';
-import { FuseKnowledgeBaseModule } from './knowledge-base/knowledge-base.module';
+import { KnowledgeBaseModule } from './knowledge-base/knowledge-base.module';
 
 @NgModule({
     imports: [
@@ -63,7 +63,7 @@ import { FuseKnowledgeBaseModule } from './knowledge-base/knowledge-base.module'
         FaqModule,
 
         // Knowledge base
-        FuseKnowledgeBaseModule
+        KnowledgeBaseModule
     ]
 })
 export class PagesModule