WARNING: javafx.scene.Node impl_cssSet Failed to set css [StyleableProperty {owningClass: javafx.scene.layout.TilePane, fieldName: prefColumns, property: -fx-pref-columns, converter: SizeConverter, initialValue: '5', inherits: false, subProperties: []}]

java.lang.ClassCastException: java.lang.Double cannot be cast to java.lang.Integer
        at javafx.scene.layout.TilePane.impl_cssSet(TilePane.java:930)


import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.TilePane;
import javafx.stage.Stage;

public class Main extends Application {

    public static void main(String[] args) {
        Application.launch(args);
    }

    @Override public void start(Stage stage) throws Exception {

        TilePane tilePane = new TilePane();
        tilePane.setStyle("-fx-pref-columns: 3; -fx-pref-rows: 2;");

        Button btns[] = new Button[6];
        for (int i=0; i<6; i++) {
            btns[i] = new Button(Integer.toString(i));
            btns[i].setStyle("-fx-padding: 20;");
            tilePane.getChildren().add(btns[i]);
        }

        stage.setScene(new Scene(tilePane));
        stage.show();
    }
}