NPE when joining areas

[Klumbumbus]

What steps will reproduce the problem?

1. I just joined overlapping buildings with shift+J. The joining was successful though.

Revision: 7988
Repository Root: http://josm.openstreetmap.de/svn
Relative URL: ^/trunk
Last Changed Author: Don-vip
Last Changed Date: 2015-01-26 21:24:30 +0100 (Mon, 26 Jan 2015)
Build-Date: 2015-01-27 02:34:34
URL: http://josm.openstreetmap.de/svn/trunk
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last Changed Rev: 7988

Identification: JOSM/1.5 (7988 en) Windows 7 32-Bit
Memory Usage: 293 MB / 742 MB (105 MB allocated, but free)
Java version: 1.8.0_31, Oracle Corporation, Java HotSpot(TM) Client VM
VM arguments: [-Djava.security.manager, -Djava.security.policy=file:C:\Program Files\Java\jre1.8.0_31\lib\security\javaws.policy, -DtrustProxy=true, -Djnlpx.home=<java.home>\bin, -Djnlpx.origFilenameArg=C:\Program Files\josm-latest.jnlp, -Djnlpx.remove=true, -Djava.util.Arrays.useLegacyMergeSort=true, -Djnlpx.heapsize=256m,768m, -Djnlpx.splashport=54587, -Djnlpx.jvm=<java.home>\bin\javaw.exe, -Djnlpx.vmargs=LURqYXZhLnV0aWwuQXJyYXlzLnVzZUxlZ2FjeU1lcmdlU29ydD10cnVlAA==]
Program arguments: [--debug]
Dataset consistency test: No problems found

Plugins:
- DirectUpload (30892)
- HouseNumberTaggingTool (30892)
- OpeningHoursEditor (30892)
- PicLayer (30892)
- Tracer2 (30927)
- buildings_tools (30892)
- download_along (30892)
- editgpx (30892)
- imagery_offset_db (30892)
- measurement (30892)
- mirrored_download (30892)
- notes (v0.9.5)
- public_transport (30892)
- reltoolbox (30892)
- reverter (30892)
- tag2link (30892)
- terracer (30892)
- turnrestrictions (30892)
- undelete (30892)
- utilsplugin2 (30892)
- wikipedia (30892)

Last errors/warnings:
- E: Failed to locate image 'error_small.png'
- W: Mappaint style "standard" (FIXME Highlight Warnings) icon "error_small.png" not found.
- E: java.lang.NullPointerException
- E: java.lang.NullPointerException

java.lang.NullPointerException
	at org.openstreetmap.josm.actions.JoinAreasAction.join(JoinAreasAction.java:480)
	at org.openstreetmap.josm.actions.JoinAreasAction.actionPerformed(JoinAreasAction.java:401)
	at javax.swing.SwingUtilities.notifyAction(Unknown Source)
	at javax.swing.JComponent.processKeyBinding(Unknown Source)
	at javax.swing.KeyboardManager.fireBinding(Unknown Source)
	at javax.swing.KeyboardManager.fireKeyboardAction(Unknown Source)
	at javax.swing.JComponent.processKeyBindingsForAllComponents(Unknown Source)
	at javax.swing.JComponent.processKeyBindings(Unknown Source)
	at javax.swing.JComponent.processKeyEvent(Unknown Source)
	at java.awt.Component.processEvent(Unknown Source)
	at java.awt.Container.processEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.KeyboardFocusManager.redispatchEvent(Unknown Source)
	at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(Unknown Source)
	at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(Unknown Source)
	at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(Unknown Source)
	at java.awt.DefaultKeyboardFocusManager.dispatchEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Window.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(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$1.doIntersectionPrivilege(Unknown Source)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue$4.run(Unknown Source)
	at java.awt.EventQueue$4.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.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)

[Don-vip]

my fault, major, release-blocking regression, working on a fix.

[Don-vip]

Ticket #11028 has been marked as a duplicate of this ticket.

[Don-vip]

In 7989/josm:

fix #11026 - NPE when joining areas (regression from r7987)