JavaFX - Caused by: java.lang.NullPointerException

[Aprendiz.Java]

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
	at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1787)
	at javafx.fxml/javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1670)
	at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
	at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
	at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
	at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
	at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
	at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
	at javafx.base/javafx.event.Event.fireEvent(Event.java:198)
	at javafx.controls/javafx.scene.control.MenuItem.fire(MenuItem.java:465)
	at javafx.controls/com.sun.javafx.scene.control.ContextMenuContent$MenuItemContainer.doSelect(ContextMenuContent.java:1380)
	at javafx.controls/com.sun.javafx.scene.control.ContextMenuContent$MenuItemContainer.lambda$createChildren$12(ContextMenuContent.java:1333)
	at javafx.base/com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
	at javafx.base/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
	at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
	at javafx.base/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
	at javafx.base/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
	at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
	at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at javafx.base/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
	at javafx.base/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
	at javafx.base/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
	at javafx.base/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
	at javafx.base/javafx.event.Event.fireEvent(Event.java:198)
	at javafx.graphics/javafx.scene.Scene$MouseHandler.process(Scene.java:3851)
	at javafx.graphics/javafx.scene.Scene$MouseHandler.access$1200(Scene.java:3579)
	at javafx.graphics/javafx.scene.Scene.processMouseEvent(Scene.java:1849)
	at javafx.graphics/javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2588)
	at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:397)
	at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
	at java.base/java.security.AccessController.doPrivileged(Native Method)
	at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:434)
	at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:390)
	at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:433)
	at javafx.graphics/com.sun.glass.ui.View.handleMouseEvent(View.java:556)
	at javafx.graphics/com.sun.glass.ui.View.notifyMouse(View.java:942)
	at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
	at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
	at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.reflect.InvocationTargetException
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at com.sun.javafx.reflect.Trampoline.invoke(MethodUtil.java:76)
	at jdk.internal.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at javafx.base/com.sun.javafx.reflect.MethodUtil.invoke(MethodUtil.java:273)
	at javafx.fxml/com.sun.javafx.fxml.MethodHelper.invoke(MethodHelper.java:83)
	at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1784)
	... 43 more
Caused by: java.lang.NullPointerException
	at gui.MainViewController.loadView(MainViewController.java:54)
	at gui.MainViewController.onMenuItemDepartmentAction(MainViewController.java:35)
	... 54 more

Estou com esse erro na hora de acionar uma janela na minha aplicação!

[Aprendiz.Java]

package gui;

import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;

import application.Main;
import gui.util.Alerts;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Alert.AlertType;
import javafx.scene.control.MenuItem;
import javafx.scene.control.ScrollPane;
import javafx.scene.layout.VBox;

public class MainViewController implements Initializable {

	@FXML
	private MenuItem menuItemSeller;
	@FXML
	private MenuItem menuItemDepartment;
	@FXML
	private MenuItem menuItemAbout;

	@FXML
	public void onMenuItemSellerAction() {
		System.out.println("onMenuItemSellerAction");
	}

	@FXML
	public void onMenuItemDepartmentAction() {
		**loadView("/gui/DepartmentList.fxml");**
	}

	@FXML
	public void onMenuItemAboutAction() {
		loadView("/gui/About.fxml");
	}

	@Override
	public void initialize(URL url, ResourceBundle rb) {

	}
	
	private synchronized void loadView(String absoluteName) {
		try {
			FXMLLoader loader = new FXMLLoader(getClass().getResource(absoluteName));
			VBox newVBox = loader.load();
			
			Scene mainScene = Main.getMainScene();
			**VBox mainVBox = (VBox) ( (ScrollPane) mainScene.getRoot()).getContent();**
			
			Node mainMenu = mainVBox.getChildren().get(0);
			mainVBox.getChildren().clear();
			mainVBox.getChildren().add(mainMenu);
			mainVBox.getChildren().addAll(newVBox.getChildren());
			
			
		}
		catch (IOException e) {
			Alerts.showAlert("IO Exception", "Error loading view", e.getMessage(), AlertType.ERROR);
		}
	}	
}

Aqui está o codigo e o erro acusa as partes em negrito!

[Aprendiz.Java]

Essa é a tela da aplicação!

essa outra tela era para surgir ao acionar o menu Department.

[PedreiroDeSoftware]

essa outra tela era para surgir ao acionar o menu Department.

No controller, olhe se alguma variável está sem a anotação @FXML.
Depois, no fxml, se os ids batem com as variaveis no controller

[Aprendiz.Java]

Dei uma verificada e não encontrei a principio algo errado com os @FXML. Estou procurando algo de errado nas configurações do projeto, caso não encontre nada de errado volto para os codigos.

[Aprendiz.Java]

Alguns problemas de configurações impediam de o aplicativo rodar. Algo haver com as versões recentes do JavaFX e eclipse.