Merge pull request #334 from backbonelabs/navigator-null-bug

added null check for navigator

app/containers/Application.js

@@ -120,19 +120,20 @@ class Application extends Component {
           return true;
         }
 
-        const routeStack = this.navigator.getCurrentRoutes();
-        const currentRoute = routeStack[routeStack.length - 1];
-        if (currentRoute.name === routes.postureMonitor.name) {
-          // Delegate to the PostureMonitor to handle this scenario
-          return true;
+        if (this.navigator) {
+          const routeStack = this.navigator.getCurrentRoutes();
+          const currentRoute = routeStack[routeStack.length - 1];
+          if (currentRoute.name === routes.postureMonitor.name) {
+            // Delegate to the PostureMonitor to handle this scenario
+            return true;
+          } else if (this.navigator.getCurrentRoutes().length > 1) {
+            // There are subsequent routes after the initial route,
+            // so pop the route stack to navigate one scene back
+            this.navigator.pop();
+            return true;
+          }
         }
 
-        if (this.navigator && this.navigator.getCurrentRoutes().length > 1) {
-          // There are subsequent routes after the initial route,
-          // so pop the route stack to navigate one scene back
-          this.navigator.pop();
-          return true;
-        }
         // There are no routes to pop, exit app
         return false;
       });