NPE with Ctrl+Z after merge overlap

[naoliv]

Using the attached example file, select both the way with name=1 and the waterway.
Run "merge overlap" and then Ctrl+Z to undo.
This is what I get:

Repository Root: http://josm.openstreetmap.de/svn
Build-Date: 2014-10-26 02:33:42
Last Changed Author: Klumbumbus
Revision: 7653
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Relative URL: ^/trunk
URL: http://josm.openstreetmap.de/svn/trunk
Last Changed Date: 2014-10-25 16:39:46 +0200 (Sat, 25 Oct 2014)
Last Changed Rev: 7653

Identification: JOSM/1.5 (7653 pt_BR) Linux Debian GNU/Linux unstable (sid)
Memory Usage: 3057 MB / 4029 MB (1794 MB allocated, but free)
Java version: 1.7.0_65, Oracle Corporation, OpenJDK 64-Bit Server VM
Java package: openjdk-7-jre:amd64-7u71-2.5.3-1
VM arguments: [-Dawt.useSystemAAFontSettings=on]
Dataset consistency test: No problems found

Plugins:
- AddrInterpolation (30737)
- Create_grid_of_ways (30762)
- FixAddresses (30737)
- ImageryCache (30738)
- OpeningHoursEditor (30737)
- PicLayer (30762)
- SimplifyArea (30762)
- buildings_tools (30762)
- download_along (30762)
- editgpx (30737)
- geotools (30762)
- graphview (30762)
- jts (30762)
- measurement (30737)
- merge-overlap (30762)
- notes (v0.9.4)
- opendata (30762)
- pdfimport (30737)
- poly (30738)
- reverter (30737)
- tagging-preset-tester (30736)
- todo (29154)
- turnrestrictions (30762)
- undelete (30762)
- utilsplugin2 (30762)

Last errors/warnings:
- W: Unable to remove primitives from TestError [tester=org.openstreetmap.josm.data.validation.tests.UnconnectedWays$UnconnectedWaterways@2fe649d, code=1301]
- W: Unable to remove primitives from TestError [tester=org.openstreetmap.josm.data.validation.tests.UnconnectedWays$UnconnectedWaterways@2fe649d, code=1301]
- W: Unable to remove primitives from TestError [tester=org.openstreetmap.josm.data.validation.tests.UnconnectedWays$UnconnectedWaterways@2fe649d, code=1301]
- W: Unable to remove primitives from TestError [tester=org.openstreetmap.josm.data.validation.tests.CrossingWays$Boundaries@40457344, code=601]
- E: java.lang.NullPointerException

java.lang.NullPointerException
	at org.openstreetmap.josm.data.osm.Way.load(Way.java:289)
	at org.openstreetmap.josm.command.DeleteCommand.undoCommand(DeleteCommand.java:142)
	at org.openstreetmap.josm.command.SequenceCommand.undoCommands(SequenceCommand.java:80)
	at org.openstreetmap.josm.command.SequenceCommand.undoCommand(SequenceCommand.java:85)
	at org.openstreetmap.josm.data.UndoRedoHandler.undo(UndoRedoHandler.java:92)
	at org.openstreetmap.josm.data.UndoRedoHandler.undo(UndoRedoHandler.java:77)
	at org.openstreetmap.josm.actions.UndoAction.actionPerformed(UndoAction.java:36)
	at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1662)
	at javax.swing.JComponent.processKeyBinding(JComponent.java:2869)
	at javax.swing.KeyboardManager.fireBinding(KeyboardManager.java:307)
	at javax.swing.KeyboardManager.fireKeyboardAction(KeyboardManager.java:263)
	at javax.swing.JComponent.processKeyBindingsForAllComponents(JComponent.java:2961)
	at javax.swing.JComponent.processKeyBindings(JComponent.java:2953)
	at javax.swing.JComponent.processKeyEvent(JComponent.java:2832)
	at java.awt.Component.processEvent(Component.java:6293)
	at java.awt.Container.processEvent(Container.java:2229)
	at java.awt.Component.dispatchEventImpl(Component.java:4872)
	at java.awt.Container.dispatchEventImpl(Container.java:2287)
	at java.awt.Component.dispatchEvent(Component.java:4698)
	at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1887)
	at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:762)
	at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1027)
	at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:899)
	at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:727)
	at java.awt.Component.dispatchEventImpl(Component.java:4742)
	at java.awt.Container.dispatchEventImpl(Container.java:2287)
	at java.awt.Window.dispatchEventImpl(Window.java:2719)
	at java.awt.Component.dispatchEvent(Component.java:4698)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:735)
	at java.awt.EventQueue.access$200(EventQueue.java:103)
	at java.awt.EventQueue$3.run(EventQueue.java:694)
	at java.awt.EventQueue$3.run(EventQueue.java:692)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
	at java.awt.EventQueue$4.run(EventQueue.java:708)
	at java.awt.EventQueue$4.run(EventQueue.java:706)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:705)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)

[Don-vip]

In 7675/josm:

see #10680 - detect invalid delete commands earlier

[Don-vip]

Fixed in [o30778:30779], [o30782:30785].