Help menu fails to show help

[dadler64]

OS: [Windows 10]
Version: [2.7.3]

About

First three help items fail to open and become disabled when the user selects any of them from the Help menu. Below are the names of the three items in question:

• Tutorial
• User's Guide
• Library Reference

This is supposed to use the JavaHelp library to open each Help menu item in its own window with a tree view to help with exploring the various pages. However since that adds unnecessary bulk to this program, I may just have these items link to their respective pages in the wiki and remove the JavaHelp dependency altogether.

Images

Help menu error dialog:

Error Log

Below is the error output when you attempt to open one of the first three Help menu items.

java.lang.NullPointerException
	at com.cburch.logisim.gui.menu.MenuHelp.showHelp(MenuHelp.java:119)
	at com.cburch.logisim.gui.menu.MenuHelp.actionPerformed(MenuHelp.java:71)
	at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1967)
	at java.desktop/javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2308)
	at java.desktop/javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:405)
	at java.desktop/javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:262)
	at java.desktop/javax.swing.AbstractButton.doClick(AbstractButton.java:369)
	at java.desktop/javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:1020)
	at java.desktop/javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:1064)
	at java.desktop/java.awt.Component.processMouseEvent(Component.java:6632)
	at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3342)
	at java.desktop/java.awt.Component.processEvent(Component.java:6397)
	at java.desktop/java.awt.Container.processEvent(Container.java:2263)
	at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5008)
	at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2321)
	at java.desktop/java.awt.Component.dispatchEvent(Component.java:4840)
	at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4918)
	at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4547)
	at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4488)
	at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2307)
	at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2762)
	at java.desktop/java.awt.Component.dispatchEvent(Component.java:4840)
	at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:772)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:389)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:95)
	at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
	at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:743)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:389)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
	at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742)
	at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)