New Slide gives exception

[ellipticview]

Version 1.7.1. To reproduce:

1. Make workdir visible on left
2. In the white area, rightclick and choose New> New Slide
3. Enter directory name (e.g. "abc") and press OK

The following exception is then found in the log:

ERROR => java.lang.reflect.InvocationTargetException
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:459)
	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$MouseHandler.process(Scene.java:3862)
	at javafx.graphics/javafx.scene.Scene.processMouseEvent(Scene.java:1849)
	at javafx.graphics/javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2590)
	at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:409)
	at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:299)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:389)
	at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:447)
	at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:411)
	at javafx.graphics/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:446)
	at javafx.graphics/com.sun.glass.ui.View.handleMouseEvent(View.java:556)
	at javafx.graphics/com.sun.glass.ui.View.notifyMouse(View.java:942)
	at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
	at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
	at java.base/java.lang.Thread.run(Thread.java:835)
Caused by: java.lang.reflect.InvocationTargetException: null
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:567)
	at com.sun.javafx.reflect.Trampoline.invoke(MethodUtil.java:76)
	at jdk.internal.reflect.GeneratedMethodAccessor22.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:567)
	at javafx.base/com.sun.javafx.reflect.MethodUtil.invoke(MethodUtil.java:273)
	at javafx.fxml/com.sun.javafx.fxml.MethodHelper.invoke(MethodHelper.java:83)
	at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1782)
	... 42 common frames omitted
Caused by: java.lang.NullPointerException: null
	at com.kodedu.controller.ApplicationController.lambda$newSlide$199(ApplicationController.java:2937)
	at java.base/java.util.Optional.ifPresent(Optional.java:183)
	at com.kodedu.controller.ApplicationController.newSlide(ApplicationController.java:2929)
	... 53 common frames omitted