Uncaught exception in adding a new entry by DOI

[hisakatha]

JabRef version JabRef 5.0-dev--snapshot--2019-08-18--master--445af8d06 on Mac OS X 10.14.6 x86_64
Java 1.8.0_221

• I have tested the latest development version from http://builds.jabref.org/master/ and the problem persists

When I add a unique new entry by DOI, the following error occurs, regardless of the library to be added to is empty or not:
Uncaught exception occurred in Thread[JavaFX Application Thread,5,main]

However, the entry is added correctly, though the error message appears.

I've tested a few DOIs and exactly the same log was generated.

Steps to reproduce the behavior:

1. Add a new entry (to a empty/non-emtpy library) by DOI

In addition, exactly the same error and log were generated when I merged entries in adding a duplicated entry by DOI.

Log File

java.lang.NullPointerException
  at org.jabref.gui.EntryTypeView.setEntryTypeForReturnAndClose(EntryTypeView.java:166)
  at org.jabref.gui.EntryTypeView.lambda$new$660(EntryTypeView.java:82)
  at org.fxmisc.easybind.EasyBind.lambda$subscribe$12(EasyBind.java:263)
  at com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:182)
  at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
  at javafx.beans.property.BooleanPropertyBase.fireValueChangedEvent(BooleanPropertyBase.java:103)
  at javafx.beans.property.BooleanPropertyBase.markInvalid(BooleanPropertyBase.java:110)
  at javafx.beans.property.BooleanPropertyBase.set(BooleanPropertyBase.java:144)
  at org.jabref.gui.EntryTypeViewModel.lambda$runFetcherWorker$588(EntryTypeViewModel.java:166)
  at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
  at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
  at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
  at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
  at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
  at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
  at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
  at javafx.event.Event.fireEvent(Event.java:198)
  at javafx.concurrent.EventHelper.fireEvent(EventHelper.java:219)
  at javafx.concurrent.Task.fireEvent(Task.java:1356)
  at javafx.concurrent.Task.setState(Task.java:723)
  at javafx.concurrent.Task$TaskCallable.lambda$call$1(Task.java:1434)
  at com.sun.javafx.application.PlatformImpl.lambda$null$5(PlatformImpl.java:295)
  at java.security.AccessController.doPrivileged(Native Method)
  at com.sun.javafx.application.PlatformImpl.lambda$runLater$6(PlatformImpl.java:294)
  at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
  at com.sun.glass.ui.mac.MacApplication._enterNestedEventLoopImpl(Native Method)
  at com.sun.glass.ui.mac.MacApplication._enterNestedEventLoop(MacApplication.java:109)
  at com.sun.glass.ui.Application.enterNestedEventLoop(Application.java:511)
  at com.sun.glass.ui.EventLoop.enter(EventLoop.java:107)
  at com.sun.javafx.tk.quantum.QuantumToolkit.enterNestedEventLoop(QuantumToolkit.java:633)
  at javafx.stage.Stage.showAndWait(Stage.java:474)
  at javafx.scene.control.HeavyweightDialog.showAndWait(HeavyweightDialog.java:162)
  at javafx.scene.control.Dialog.showAndWait(Dialog.java:341)
  at org.jabref.gui.importer.NewEntryAction.execute(NewEntryAction.java:60)
  at org.jabref.gui.actions.JabRefAction.lambda$new$1017(JabRefAction.java:29)
  at org.controlsfx.control.action.Action.handle(Action.java:419)
  at org.controlsfx.control.action.Action.handle(Action.java:64)
  at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
  at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
  at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
  at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
  at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
  at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
  at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
  at javafx.event.Event.fireEvent(Event.java:198)
  at javafx.scene.control.MenuItem.fire(MenuItem.java:462)
  at com.sun.javafx.scene.control.GlobalMenuAdapter.lambda$bindMenuItemProperties$2(GlobalMenuAdapter.java:153)
  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.scene.control.MenuItem.fire(MenuItem.java:462)
  at com.sun.javafx.tk.quantum.GlassSystemMenu$1.action(GlassSystemMenu.java:238)