crash and history say "move 2 nodes" with only one node in the layer

[marc_marc]

What steps will reproduce the problem?

I was unable to reproduce the problem, here is what was done just before the crash

1. select 3 items with ctrl-a (one node and 2 related relations)
2. delete one tag
3. inadvertently moving the node (the history stack say "moving 2 nodes" but the single layer used at the time of the crash contains only one node)

Undo+redo doesn't crash.

What is the expected result?

no crash :)

What happens instead?

crash popup :)

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: 2017-12-31 03:09:43 +0100 (Sun, 31 Dec 2017)
Build-Date:2017-12-31 02:33:46
Revision:13265
Relative:URL: ^/trunk

Identification: JOSM/1.5 (13265 fr) Linux CentOS Linux 7 (Core)
Memory Usage: 1051 MB / 1717 MB (324 MB allocated, but free)
Java version: 1.8.0_151-b12, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 1600x900
Maximum Screen Size: 1600x900
Java package: java-1.8.0-openjdk:x86_64-1.8.0.151
WebStart package: icedtea-web:x86_64-1.6.2
VM arguments: [-Dicedtea-web.bin.name=javaws.itweb, -Dicedtea-web.bin.location=/usr/bin/javaws.itweb]
Dataset consistency test: No problems found

Plugins:
+ HouseNumberTaggingTool (33904)
+ Mapillary (v1.5.9)
+ OpeningHoursEditor (33876)
+ RoadSigns (33798)
+ apache-commons (33668)
+ apache-http (32699)
+ conflation (0.5.6)
+ continuosDownload (68)
+ ejml (32680)
+ geotools (33958)
+ imagery_offset_db (33774)
+ jogl (1.1.0)
+ jts (32699)
+ log4j (32699)
+ opendata (34019)
+ photo_geotagging (33967)
+ photoadjust (33746)
+ pt_assistant (33860)
+ reverter (33865)
+ tag2link (33934)
+ todo (30303)
+ turnrestrictions (33780)
+ utilsplugin2 (33991)
+ wikipedia (33993)

Tagging presets:
+ https://raw.github<user.name>content.com/yopaseopor/traffic_signs_preset_JOSM/master/CH.zip
+ https://josm.openstreetmap.de/josmfile?page=Presets/Light_sources&zip=1
+ http://zibi.openstreetmap.org.pl/kendzi/k/Simple3dPreset/s3db-preset.zip
+ https://josm.openstreetmap.de/josmfile?page=Presets/Addr2&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/BuildingPreset&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/ParkingLanes&zip=1
+ https://raw.github<user.name>content.com/species/josm-preset-wheelchair/master/sidewalks_kerbs.xml
+ http://osmtools.de/josm/steps.xml

Map paint styles:
- https://josm.openstreetmap.de/josmfile?page=Styles/ParkingLanes&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Coloured_Streets&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/BesideTheRoad_Speed&zip=1
- https://raw.github<user.name>content.com/species/josm-preset-traffic_sign_direction/master/direction.mapcss
- https://josm.openstreetmap.de/josmfile?page=Styles/Enhanced_Lane_and_Road_Attributes&zip=1
- https://www.dropbox.com/s/qo3ai47fpv241jf/Styles_Fixme_and_Notes.zip?raw=1
- https://josm.openstreetmap.de/josmfile?page=Styles/SimpleBuildingTags&zip=1
- https://raw.github<user.name>content.com/yopaseopor/traffic_signs_style_JOSM/master/Styles_Traffic_signs_EUR.zip
- https://josm.openstreetmap.de/josmfile?page=Styles/light_source&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Sidewalks&zip=1
- https://raw.github<user.name>content.com/species/josm-preset-wheelchair/master/sidewalks_kerbs.mapcss
- https://josm.openstreetmap.de/josmfile?page=Styles/Noname&zip=1

Validator rules:
+ https://raw.github<user.name>content.com/nlehuby/transport_mapcss/master/transport.validator.mapcss
+ http://www.openrailwaymap.org/validator/openrailwaymap.validator.mapcss
+ https://raw.github<user.name>content.com/stefan-a-bauer/josm-validators/master/mtb.validator.mapcss

Last errors/warnings:
- W: Invalid jar file ''<josm.pref>/plugins/opendata.jar.new'' (exists: false, canRead: false)
- W: Unable to initialize OpeningHourTest because no JavaScript engine has been found
- W: Unable to initialize OpeningHourTest because no JavaScript engine has been found
- W: No configuration settings found.  Using hardcoded default values for all pools.
- 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 (33) of JOSM
java.lang.NullPointerException
	at org.openstreetmap.josm.actions.MoveAction.actionPerformed(MoveAction.java:154)
	at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1663)
	at javax.swing.JComponent.processKeyBinding(JComponent.java:2882)
	at javax.swing.KeyboardManager.fireBinding(KeyboardManager.java:307)
	at javax.swing.KeyboardManager.fireKeyboardAction(KeyboardManager.java:263)
	at javax.swing.JComponent.processKeyBindingsForAllComponents(JComponent.java:2974)
	at javax.swing.JComponent.processKeyBindings(JComponent.java:2966)
	at javax.swing.JComponent.processKeyEvent(JComponent.java:2845)
	at java.awt.Component.processEvent(Component.java:6310)
	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.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1954)
	at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:806)
	at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1074)
	at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:945)
	at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:771)
	at java.awt.Component.dispatchEventImpl(Component.java:4760)
	at java.awt.Container.dispatchEventImpl(Container.java:2294)
	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 #15765.