On iOS add error handling for getRouteselector (#2394)

client/ios/NetBirdSDK/client.go

@@ -271,7 +271,14 @@ func (c *Client) GetRoutesSelectionDetails() (*RoutesSelectionDetails, error) {
 	}
 
 	routesMap := engine.GetClientRoutesWithNetID()
-	routeSelector := engine.GetRouteManager().GetRouteSelector()
+	routeManager := engine.GetRouteManager()
+	if routeManager == nil {
+		return nil, fmt.Errorf("could not get route manager")
+	}
+	routeSelector := routeManager.GetRouteSelector()
+	if routeSelector == nil {
+		return nil, fmt.Errorf("could not get route selector")
+	}
 
 	var routes []*selectRoute
 	for id, rt := range routesMap {