java.nio.file.ClosedWatchServiceException
  at sun.nio.fs.AbstractPoller.invoke(AbstractPoller.java:216)
  at sun.nio.fs.AbstractPoller.register(AbstractPoller.java:125)
  at sun.nio.fs.LinuxWatchService.register(LinuxWatchService.java:90)
  at sun.nio.fs.UnixPath.register(UnixPath.java:897)
  at sun.nio.fs.AbstractPath.register(AbstractPath.java:104)
  at org.jabref.gui.util.DefaultFileUpdateMonitor.addListenerForFile(DefaultFileUpdateMonitor.java:78)
  at org.jabref.gui.util.ThemeLoader.addAndWatchForChanges(ThemeLoader.java:100)
  at org.jabref.gui.util.ThemeLoader.installCss(ThemeLoader.java:81)
  at org.jabref.gui.util.BaseDialog.<init>(BaseDialog.java:30)
  at org.jabref.gui.preferences.PreferencesDialog.<init>(PreferencesDialog.java:63)
  at org.jabref.gui.actions.ShowPreferencesAction.execute(ShowPreferencesAction.java:19)
  at org.jabref.gui.actions.JabRefAction.lambda$2(JabRefAction.java:29)
  at org.controlsfx.control.action.Action.handle(Action.java:419)
  at org.controlsfx.control.action.Action.handle(Action.java:64)
  at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
  at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
  at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
  at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
  at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
  at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
  at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
  at javafx.event.Event.fireEvent(Event.java:198)
  at javafx.scene.control.MenuItem.fire(MenuItem.java:462)
  at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.doSelect(ContextMenuContent.java:1405)
  at com.sun.javafx.scene.control.skin.ContextMenuContent$MenuItemContainer.lambda$createChildren$6(ContextMenuContent.java:1358)
  at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
  at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
  at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
  at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
  at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
  at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
  at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
  at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
  at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
  at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
  at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
  at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
  at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
  at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
  at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
  at javafx.event.Event.fireEvent(Event.java:198)
  at javafx.scene.Scene$MouseHandler.process(Scene.java:3757)
  at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
  at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
  at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
  at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:394)
  at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
  at java.security.AccessController.doPrivileged(Native Method)
  at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:432)
  at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
  at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:431)
  at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
  at com.sun.glass.ui.View.notifyMouse(View.java:937)
  at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
  at com.sun.glass.ui.gtk.GtkApplication.lambda$null$5(GtkApplication.java:139)
  at java.lang.Thread.run(Thread.java:748)