NPE at JoinAreasAction.join

[CKSaunders]

What steps will reproduce the problem?

1. Editing after validation check

What is the expected result?

Save edits

What happens instead?

Error comes up

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

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2018-03-26 22:16:39 +0200 (Mon, 26 Mar 2018)
Build-Date:2018-03-26 20:45:23
Revision:13576
Redirecting:to URL 'https://josm.openstreetmap.de/svn/trunk':
Relative:URL: ^/trunk

Identification: JOSM/1.5 (13576 en) Windows 7 64-Bit
OS Build number: Windows 7 Professional (7601)
Memory Usage: 247 MB / 247 MB (56 MB allocated, but free)
Java version: 1.8.0_161-b12, Oracle Corporation, Java HotSpot(TM) Client VM
Screen: \Display0 1920x1080
Maximum Screen Size: 1920x1080
VM arguments: [-Djava.security.manager, -Djava.security.policy=file:<java.home>\lib\security\javaws.policy, -DtrustProxy=true, -Djnlpx.home=<java.home>\bin, -Djnlpx.origFilenameArg=%<user.name>Profile%\AppData\LocalLow\Sun\Java\Deployment\cache\6.0\56\1ee8cfb8-22a03ed1, -Djnlpx.remove=false, -Djava.util.Arrays.useLegacyMergeSort=true, -Djnlpx.splashport=49289, -Djnlp.application.href=https://josm.openstreetmap.de/download/josm.jnlp, -Djnlpx.jvm=<java.home>\bin\javaw.exe]
Dataset consistency test: No problems found

Plugins:
+ buildings_tools (34109)
+ imagery_offset_db (34109)
+ scripting (30783)
+ turnrestrictions (34129)

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-2 (64) of javawsApplicationThreadGroup
java.lang.NullPointerException
	at org.openstreetmap.josm.actions.JoinAreasAction.join(JoinAreasAction.java:550)
	at org.openstreetmap.josm.actions.JoinAreasAction.actionPerformed(JoinAreasAction.java:474)
	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$3.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue$4.run(Unknown Source)
	at java.awt.EventQueue$4.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.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]

In 13635/josm:

fix #16191 - NPE