added condition to check if view is available

MVMCoreUI/Managers/SubNav/SubNavManagerController.swift

@@ -345,7 +345,10 @@ open class SubNavManagerController: ViewController, MVMCoreViewManagerProtocol,
     }
     
     @objc public func getAccessibilityElements() -> [Any]? {
-        [tabs, subNavigationController.view!]
+        guard let navigationControllerView = subNavigationController.view else {
+            return [tabs]
+        }
+        return [tabs, navigationControllerView]
     }
 
     open override func observeForResponseJSONUpdates() {