unexpected exception occurred when trying to merge-overlap two ways.

[donal.hunt@…]

What steps will reproduce the problem?

1. open ​http://tasks.hotosm.org/project/3404#task/938
2. open the task in josm.
3. attempt to merge-overlap the 331343676 and 515081914 ways (validator should identify it as an overlapping way.

What is the expected result?

No exception thrown.

What happens instead?

Exception is thrown.

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

URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2017-07-31 01:02:55 +0200 (Mon, 31 Jul 2017)
Build-Date:2017-07-31 01:53:17
Revision:12545
Relative:URL: ^/trunk

Identification: JOSM/1.5 (12545 en) Linux Debian GNU/Linux 9.1 (stretch)
Memory Usage: 1456 MB / 3563 MB (395 MB allocated, but free)
Java version: 1.8.0_141-8u141-b15-1~deb9u1-b15, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 3200x1200, :0.1 1600x1200
Maximum Screen Size: 3200x1200
Java package: openjdk-8-jre:amd64-8u141-b15-1~deb9u1
WebStart package: icedtea-netx:amd64-1.6.2-3.1
Java ATK Wrapper package: libatk-wrapper-java:all-0.33.3-13
VM arguments: [-Dicedtea-web.bin.name=javaws, -Dicedtea-web.bin.location=/usr/bin/javaws, -Djava.security.manager, -Djava.security.policy=/etc/icedtea-web/javaws.policy]
Dataset consistency test: No problems found

Plugins:
+ ShapeTools (1220)
+ buildings_tools (33004)
+ merge-overlap (33436)

Map paint styles:
+ https://github.com/hotosm/HDM-JOSM-style/archive/master.zip
+ https://www.dropbox.com/s/qo3ai47fpv241jf/Styles_Fixme_and_Notes.zip?raw=1

Last errors/warnings:
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- W: java.io.IOException: Attribution is not loaded yet
- 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-1 (31) of JOSM
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)

[Don-vip]

Closed as duplicate of #14971.