header, isNavBarCollapsed observable: filter out undefined state that can occur when using AoT compilation

src/app/app.component.ts

@@ -37,6 +37,13 @@ export class AppComponent implements OnDestroy, OnInit {
     translate.setDefaultLang('en');
     // the lang to use, if the lang isn't available, it will use the current loader to get them
     translate.use('en');
+
+    this.onResize({
+      target: {
+        innerWidth: 800,
+        innerHeight: 600
+      }
+    });
   }
 
   ngOnInit() {