NPE when trying to combine areas

[Andre68]

What steps will reproduce the problem?

1. Select two overlapping buildings
2. Selecting "More tools"/"Merge overlap"

What is the expected result?

The builds are merged

What happens instead?

NPE

Please provide any additional information below. Attach a screenshot if possible.

Build-Date:2017-06-27 09:03:11
Revision:12435
Is-Local-Build:true

Identification: JOSM/1.5 (12435 SVN de) Linux Mint 17.3 Rosa
Memory Usage: 894 MB / 2731 MB (502 MB allocated, but free)
Java version: 1.8.0_131-b11, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: :0.0 1920x1080
Maximum Screen Size: 1920x1080
Program arguments: [track-2017-06-26-20-31.gpx, waypoints-2017-06-26-20-39.gpx, ../wf.osm]
Dataset consistency test: No problems found

Plugins:
+ FixAddresses (33182)
+ ImproveWay (12)
+ Mapillary (v1.5.5)
+ OpeningHoursEditor (33185)
+ RoadSigns (33204)
+ SimplifyArea (33004)
+ alignways (33182)
+ apache-commons (32994)
+ apache-http (32699)
+ download_along (32946)
+ editgpx (33004)
+ graphview (33004)
+ imagery_offset_db (33316)
+ lakewalker (33161)
+ log4j (32699)
+ measurement (33088)
+ merge-overlap (33154)
+ osmarender (33004)
+ pbf (33241)
+ photo_geotagging (33088)
+ public_transport (33166)
+ public_transport_layer (33350)
+ reverter (33088)
+ routing (33004)
+ tageditor (33021)
+ turnlanes (33294)
+ turnlanes-tagging (254)
+ turnrestrictions (33088)
+ undelete (33374)
+ utilsplugin2 (33328)
+ waydownloader (33167)

Map paint styles:
- https://josm.openstreetmap.de/josmfile?page=Styles/Enhanced_Lane_and_Road_Attributes&zip=1

Last errors/warnings:
- E: Fehler beim Laden des Bildes 'Flag, Blue'
- E: Fehler beim Laden des Bildes 'Flag, Blue'
- E: Fehler beim Laden des Bildes 'Flag, Blue'
- E: Fehler beim Laden des Bildes 'Flag, Blue'
- E: Fehler beim Laden des Bildes 'Flag, Blue'
- E: Fehler beim Laden des Bildes 'Flag, Blue'
- E: Fehler beim Laden des Bildes 'Flag, Blue'
- E: Fehler beim Laden des Bildes 'Flag, Blue'
- E: Fehler beim Laden des Bildes 'Flag, Blue'
- E: Handled by bug report queue: java.lang.NullPointerException


=== REPORTED CRASH DATA ===
BugReportExceptionHandler#handleException:
No data collected.

Warning issued by: BugReportExceptionHandler#handleException

=== STACK TRACE ===
Thread: AWT-EventQueue-0 (19) of main
java.lang.NullPointerException
	at org.openstreetmap.josm.gui.conflict.tags.RelationMemberConflictResolverModel.prepareDefaultRelationDecisions(RelationMemberConflictResolverModel.java:227)
	at org.openstreetmap.josm.gui.conflict.tags.CombinePrimitiveResolverDialog.prepareDefaultDecisions(CombinePrimitiveResolverDialog.java:311)
	at org.openstreetmap.josm.gui.conflict.tags.CombinePrimitiveResolverDialog.prepareDefaultDecisions(CombinePrimitiveResolverDialog.java:301)
	at mergeoverlap.MergeOverlapAction.combineWaysWorker(MergeOverlapAction.java:556)
	at mergeoverlap.MergeOverlapAction.actionPerformed(MergeOverlapAction.java:214)
	at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
	at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
	at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
	at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
	at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
	at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
	at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
	at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:289)
	at java.awt.Component.processMouseEvent(Component.java:6533)
	at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
	at java.awt.Component.processEvent(Component.java:6298)
	at java.awt.Container.processEvent(Container.java:2236)
	at java.awt.Component.dispatchEventImpl(Component.java:4889)
	at java.awt.Container.dispatchEventImpl(Container.java:2294)
	at java.awt.Component.dispatchEvent(Component.java:4711)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
	at java.awt.Container.dispatchEventImpl(Container.java:2280)
	at java.awt.Window.dispatchEventImpl(Window.java:2746)
	at java.awt.Component.dispatchEvent(Component.java:4711)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
	at java.awt.EventQueue.access$500(EventQueue.java:97)
	at java.awt.EventQueue$3.run(EventQueue.java:709)
	at java.awt.EventQueue$3.run(EventQueue.java:703)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:90)
	at java.awt.EventQueue$4.run(EventQueue.java:731)
	at java.awt.EventQueue$4.run(EventQueue.java:729)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)