Erro memento Desktop! Help-me, please!

[Fernando N.P.F]

Hello, I am brazilian, my english is very bad!

But,

Help me, please! Erro memento Desktop.

When I try to access one of my libraries the following error appears:

The exception stacktrace was:

java.lang.NullPointerException

at org.mapdb.BTreeMap.get(BTreeMap.java:593)

at org.mapdb.BTreeMap.get(BTreeMap.java:589)

at com.luckydroid.mementofx.controllers.LibraryController.pullEntries(LibraryController.java:300)

at com.luckydroid.mementofx.controllers.LibraryController.onLoadEntries(LibraryController.java:332)

at com.luckydroid.mementofx.controllers.LibraryController.lambda$init$95(LibraryController.java:151)

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:54)

at javafx.event.Event.fireEvent(Event.java:198)

at javafx.concurrent.EventHelper.fireEvent(EventHelper.java:219)

at javafx.concurrent.Service.fireEvent(Service.java:853)

at javafx.concurrent.Service.lambda$new$490(Service.java:554)

at com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:182)

at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)

at javafx.beans.property.ObjectPropertyBase.fireValueChangedEvent(ObjectPropertyBase.java:105)

at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112)

at javafx.beans.property.ObjectPropertyBase.access$000(ObjectPropertyBase.java:51)

at javafx.beans.property.ObjectPropertyBase$Listener.invalidated(ObjectPropertyBase.java:233)

at com.sun.javafx.binding.ExpressionHelper$SingleInvalidation.fireValueChangedEvent(ExpressionHelper.java:137)

at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)

at javafx.beans.property.ObjectPropertyBase.fireValueChangedEvent(ObjectPropertyBase.java:105)

at javafx.beans.property.ObjectPropertyBase.markInvalid(ObjectPropertyBase.java:112)

at javafx.beans.property.ObjectPropertyBase.set(ObjectPropertyBase.java:146)

at javafx.concurrent.Task.setState(Task.java:696)

at javafx.concurrent.Task$TaskCallable.lambda$call$500(Task.java:1434)

at com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)

at java.security.AccessController.doPrivileged(Native Method)

at com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)

at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)

at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)

at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)

at java.lang.Thread.run(Thread.java:745)

What is this? Help me, please!