RPW crash while exporting resource pack; MC version 18w16a

[TastyDucks]

What happened?

Crash report generated while attempting to export resource pack to Minecraft.

Steps to reproduce:

1. Load resource pack project.
2. Add custom sounds via the tool.
3. Click on the export option under "Project".

Crash report (if any)

## RPW 4.5.2 CRASH REPORT ##

Please, report this issue on GitHub (use the button below).
If possible, include THIS WHOLE LOG in the report.


Alternatively, you can send this log to MightyPork.
	E-mail: ondra@ondrovo.com


### SYSTEM INFO ###


 Key               | Value 
-------------------|-------------------------------
 Runtime name      | Java(TM) SE Runtime Environment
 Java version      | 1.8.0_161
 Java vendor       | Oracle Corporation
 Java path         | C:\Program Files\Java\jre1.8.0_161
 OS name           | Windows 10
 OS arch           | amd64
 File encoding     | Cp1252
 Launch dir        | C:\Users\TastyDucks\Downloads\temporary_containment_bin
 RPW version       | 4.5.2
 Library version   | 18w15a
 RPW path          | C:\Users\TastyDucks\AppData\Roaming\.mcRPW
 Minecraft path    | C:\Users\TastyDucks\AppData\Roaming\.minecraft


### STACK TRACE ###

java.lang.ClassCastException: javax.swing.plaf.nimbus.DerivedColor$UIResource cannot be cast to javax.swing.Painter
at javax.swing.plaf.nimbus.NimbusStyle.getBackgroundPainter(Unknown Source)
at javax.swing.plaf.nimbus.SynthPainterImpl.paintBackground(Unknown Source)
at javax.swing.plaf.nimbus.SynthPainterImpl.paintPanelBackground(Unknown Source)
at javax.swing.plaf.synth.SynthPanelUI.update(Unknown Source)
at javax.swing.JComponent.paintComponent(Unknown Source)
at javax.swing.JComponent.paint(Unknown Source)
at javax.swing.JComponent.paintToOffscreen(Unknown Source)
at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(Unknown Source)
at javax.swing.RepaintManager$PaintManager.paint(Unknown Source)
at javax.swing.RepaintManager.paint(Unknown Source)
at javax.swing.JComponent._paintImmediately(Unknown Source)
at javax.swing.JComponent.paintImmediately(Unknown Source)
at javax.swing.RepaintManager$4.run(Unknown Source)
at javax.swing.RepaintManager$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
at javax.swing.RepaintManager.prePaintDirtyRegions(Unknown Source)
at javax.swing.RepaintManager.access$1200(Unknown Source)
at javax.swing.RepaintManager$ProcessingRunnable.run(Unknown Source)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$500(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

### FULL LOG ###

[ i ] Main logger initialized.
[ i ] 2018/04/19 18:03:19
[ i ] ResourcePack Workbench v.4.5.2 (#452)
[ # ] Init started...
[ - ] Project 'Factory': Creating backup copy...
[ - ] Project 'Factory': Copying - done.
[ - ] Project 'Factory': Loading from workdir
[ ] Adding RPW_README.txt to the pack
[ - ] Checking Minecraft installation.
[ - ] Initializing configuration manager.
[ - ] Checking working directory.
[ ] Last run version: 4.5.2 (#452)
[ i ] Using library version: 18w15a
[ - ] Loading GUI icons
[ - ] Loading GUI icons - done.
[ ] Initializing RSyntaxTextArea
[ - ] Loading help pages
[ # ] Initializing Sources
[ - ] Loading vanilla structure
[ - ] Loading help pages - done.
[ - ] Loading vanilla structure - done.
[ - ] Erasing library cache
[ - ] Loading resourcepacks...
[ # ] Initializing Sources - done.
[ - ] Building main window.
[ - ] Downloading update info
[ - ] Opening last project (if any).
[ # ] Loading project Factory
[ - ] Project 'Factory': Creating backup copy...
[ - ] Project 'Factory': Copying - done.
[ - ] Project 'Factory': Loading from workdir
[ ] Adding RPW_README.txt to the pack
[ - ] Downloading update info - done.
[ i ] Your version is up-to-date.
[!E!] Error listing folder C:\Users\TastyDucks\AppData\Roaming.mcRPW\library\vanilla\assets\minecraft\sounds
[!E!] java.lang.NullPointerException
[!E!] at net.mightypork.rpw.utils.files.FileUtils.listDirectory(FileUtils.java:247)
[!E!] at net.mightypork.rpw.utils.files.FileUtils.listDirectory(FileUtils.java:226)
[!E!] at net.mightypork.rpw.tree.filesystem.DirectoryFsTreeNode.(DirectoryFsTreeNode.java:73)
[!E!] at net.mightypork.rpw.gui.windows.dialogs.DialogSoundWizard.rebuildFileTree(DialogSoundWizard.java:590)
[!E!] at net.mightypork.rpw.gui.windows.dialogs.DialogSoundWizard.initLists(DialogSoundWizard.java:465)
[!E!] at net.mightypork.rpw.gui.windows.dialogs.DialogSoundWizard.initGui(DialogSoundWizard.java:460)
[!E!] at net.mightypork.rpw.gui.windows.RpwDialog.createDialog(RpwDialog.java:144)
[!E!] at net.mightypork.rpw.gui.windows.dialogs.DialogSoundWizard.(DialogSoundWizard.java:94)
[!E!] at net.mightypork.rpw.tasks.Tasks.taskOpenSoundWizard(Tasks.java:882)
[!E!] at net.mightypork.rpw.gui.widgets.MenuMain$43.actionPerformed(MenuMain.java:898)
[!E!] at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
[!E!] at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
[!E!] at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
[!E!] at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
[!E!] at javax.swing.AbstractButton.doClick(Unknown Source)
[!E!] at javax.swing.plaf.basic.BasicMenuItemUI.doClick(Unknown Source)
[!E!] at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(Unknown Source)
[!E!] at java.awt.Component.processMouseEvent(Unknown Source)
[!E!] at javax.swing.JComponent.processMouseEvent(Unknown Source)
[!E!] at java.awt.Component.processEvent(Unknown Source)
[!E!] at java.awt.Container.processEvent(Unknown Source)
[!E!] at java.awt.Component.dispatchEventImpl(Unknown Source)
[!E!] at java.awt.Container.dispatchEventImpl(Unknown Source)
[!E!] at java.awt.Component.dispatchEvent(Unknown Source)
[!E!] at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
[!E!] at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
[!E!] at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
[!E!] at java.awt.Container.dispatchEventImpl(Unknown Source)
[!E!] at java.awt.Window.dispatchEventImpl(Unknown Source)
[!E!] at java.awt.Component.dispatchEvent(Unknown Source)
[!E!] at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
[!E!] at java.awt.EventQueue.access$500(Unknown Source)
[!E!] at java.awt.EventQueue$3.run(Unknown Source)
[!E!] at java.awt.EventQueue$3.run(Unknown Source)
[!E!] at java.security.AccessController.doPrivileged(Native Method)
[!E!] at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
[!E!] at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
[!E!] at java.awt.EventQueue$4.run(Unknown Source)
[!E!] at java.awt.EventQueue$4.run(Unknown Source)
[!E!] at java.security.AccessController.doPrivileged(Native Method)
[!E!] at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
[!E!] at java.awt.EventQueue.dispatchEvent(Unknown Source)
[!E!] at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
[!E!] at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
[!E!] at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
[!E!] at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
[!E!] at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
[!E!] at java.awt.EventDispatchThread.run(Unknown Source)
[!E!]
[ ] Dialog open: Sound Wizard
[ ] Dialog closed: Sound Wizard
[ ] Dialog open: Export
[ ] Dialog closed: Export
[ ] Dialog open: Exporting project
[ # ] Exporting project "Factory" to C:\Users\TastyDucks\AppData\Roaming.minecraft\resourcepacks\Factory.zip
[ - ] Preparing zip builder.
[ - ] Exporting included extra files.
[ - ] Exporting custom sounds.
[ ] + assets/minecraft/sounds/ambiance_city_night.ogg
[ ] + assets/minecraft/sounds/ambiance_elevator.ogg
[ ] + assets/minecraft/sounds/ambiance_jet_flyby.ogg
[ ] + assets/minecraft/sounds/ambiance_launch_voice.ogg
[ ] + assets/minecraft/sounds/ambiance_mortar_distant_1.ogg
[ ] + assets/minecraft/sounds/ambiance_mortar_distant_2.ogg
[ ] + assets/minecraft/sounds/ambiance_mortar_distant_3.ogg
[ ] + assets/minecraft/sounds/ambiance_mortar_distant_4.ogg
[ ] + assets/minecraft/sounds/ambiance_mortar_distant_many.ogg
[ ] + assets/minecraft/sounds/ambiance_mortar_fly.ogg
[ ] + assets/minecraft/sounds/ambiance_mortar_hit.ogg
[ ] + assets/minecraft/sounds/ambiance_overwatch_1.ogg
[ ] + assets/minecraft/sounds/ambiance_overwatch_2.ogg
[ ] + assets/minecraft/sounds/ambiance_overwatch_3.ogg
[ ] + assets/minecraft/sounds/ambiance_overwatch_4.ogg
[ ] + assets/minecraft/sounds/ambiance_overwatch_5.ogg
[ ] + assets/minecraft/sounds/ambiance_overwatch_6.ogg
[ ] + assets/minecraft/sounds/ambiance_siren_1.ogg
[ ] + assets/minecraft/sounds/ambiance_siren_2.ogg
[ ] + assets/minecraft/sounds/ambiance_steam.ogg
[ ] + assets/minecraft/sounds/ambiance_structure_groan_1.ogg
[ ] + assets/minecraft/sounds/ambiance_structure_groan_2.ogg
[ ] + assets/minecraft/sounds/ambiance_structure_groan_3.ogg
[ ] + assets/minecraft/sounds/ambiance_structure_groan_4.ogg
[ ] + assets/minecraft/sounds/ambiance_trump_introduction.ogg
[ ] + assets/minecraft/sounds/ambiance_warehouse_1.ogg
[ ] + assets/minecraft/sounds/music_drums_1.ogg
[ ] + assets/minecraft/sounds/music_drums_2.ogg
[ ] + assets/minecraft/sounds/music_drums_3.ogg
[ ] + assets/minecraft/sounds/music_surface_tension.ogg
[ - ] Exporting custom languages.
[ - ] Exporting configuration files.
[ ] + pack.png
[ ] + readme.txt
[ ] + assets/minecraft/sounds.json
[ ] + pack.mcmeta
[ i ] Using resource pack format: 4
[ - ] Exporting project assets.
[ - ] Adding project asset files.
[ ] Writing to MC options: resourcePacks:["Factory.zip"]
[ i ] Minecraft config file was changed.
[ # ] Exporting project "Factory" to C:\Users\TastyDucks\AppData\Roaming.minecraft\resourcepacks\Factory.zip - done.
[ i ] Export successful.
[!E!] Unhandled error, opening error screen.
[!E!] java.lang.ClassCastException: javax.swing.plaf.nimbus.DerivedColor$UIResource cannot be cast to javax.swing.Painter
[!E!] at javax.swing.plaf.nimbus.NimbusStyle.getBackgroundPainter(Unknown Source)
[!E!] at javax.swing.plaf.nimbus.SynthPainterImpl.paintBackground(Unknown Source)
[!E!] at javax.swing.plaf.nimbus.SynthPainterImpl.paintPanelBackground(Unknown Source)
[!E!] at javax.swing.plaf.synth.SynthPanelUI.update(Unknown Source)
[!E!] at javax.swing.JComponent.paintComponent(Unknown Source)
[!E!] at javax.swing.JComponent.paint(Unknown Source)
[!E!] at javax.swing.JComponent.paintToOffscreen(Unknown Source)
[!E!] at javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(Unknown Source)
[!E!] at javax.swing.RepaintManager$PaintManager.paint(Unknown Source)
[!E!] at javax.swing.RepaintManager.paint(Unknown Source)
[!E!] at javax.swing.JComponent._paintImmediately(Unknown Source)
[!E!] at javax.swing.JComponent.paintImmediately(Unknown Source)
[!E!] at javax.swing.RepaintManager$4.run(Unknown Source)
[!E!] at javax.swing.RepaintManager$4.run(Unknown Source)
[!E!] at java.security.AccessController.doPrivileged(Native Method)
[!E!] at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
[!E!] at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
[!E!] at javax.swing.RepaintManager.paintDirtyRegions(Unknown Source)
[!E!] at javax.swing.RepaintManager.prePaintDirtyRegions(Unknown Source)
[!E!] at javax.swing.RepaintManager.access$1200(Unknown Source)
[!E!] at javax.swing.RepaintManager$ProcessingRunnable.run(Unknown Source)
[!E!] at java.awt.event.InvocationEvent.dispatch(Unknown Source)
[!E!] at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
[!E!] at java.awt.EventQueue.access$500(Unknown Source)
[!E!] at java.awt.EventQueue$3.run(Unknown Source)
[!E!] at java.awt.EventQueue$3.run(Unknown Source)
[!E!] at java.security.AccessController.doPrivileged(Native Method)
[!E!] at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
[!E!] at java.awt.EventQueue.dispatchEvent(Unknown Source)
[!E!] at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
[!E!] at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
[!E!] at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
[!E!] at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
[!E!] at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
[!E!] at java.awt.EventDispatchThread.run(Unknown Source)
[!E!]

~~~ END OF REPORT ~~~