refactor(demo)!: update implementation of TabbedDemo

Author: javier-godoy

src/test/java/com/flowingcode/vaadin/addons/errorwindow/ErrorwindowDemoView.java

@@ -2,22 +2,19 @@
 
 import com.flowingcode.vaadin.addons.DemoLayout;
 import com.flowingcode.vaadin.addons.GithubLink;
-import com.flowingcode.vaadin.addons.demo.impl.TabbedDemoImpl;
-import com.vaadin.flow.component.orderedlayout.VerticalLayout;
+import com.flowingcode.vaadin.addons.demo.TabbedDemo;
 import com.vaadin.flow.router.Route;
 
 @SuppressWarnings("serial")
 @Route(value = "error-window", layout = DemoLayout.class)
 @GithubLink("https://github.com/FlowingCode/ErrorWindowAddon")
-public class ErrorwindowDemoView extends VerticalLayout {
+public class ErrorwindowDemoView extends TabbedDemo {
 
 	private static final String ERROR_DEMO = "Error Window Demo";
 	private static final String ERROR_SOURCE = "https://github.com/FlowingCode/ErrorWindowAddon/blob/master/src/test/java/com/flowingcode/vaadin/addons/errorwindow/ErrorwindowDemoView.java";
 
 	public ErrorwindowDemoView() {
-		TabbedDemoImpl<ErrorwindowDemo> errorDemo = new TabbedDemoImpl<>(new ErrorwindowDemo(), ERROR_DEMO,
-				ERROR_SOURCE);
-		add(errorDemo);
+		addDemo(new ErrorwindowDemo(), ERROR_DEMO, ERROR_SOURCE);		
 		setSizeFull();
 	}