NPE: Cannot invoke "java.util.Collection.iterator()" because "objects" is null

[RubenKelevra]

What steps will reproduce the problem?

No idea

What is the expected result?

No crash

What happens instead?

Crash

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

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2023-01-03 21:28:24 +0100 (Tue, 03 Jan 2023)
Revision:18622
Build-Date:2023-01-04 02:30:56
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (18622 en) Linux EndeavourOS Linux
Memory Usage: 646 MB / 3922 MB (120 MB allocated, but free)
Java version: 19.0.1+10, N/A, OpenJDK 64-Bit Server VM
Look and Feel: com.sun.java.swing.plaf.gtk.GTKLookAndFeel
Screen: :0.0 1920×1080 (scaling 1.00×1.00)
Maximum Screen Size: 1920×1080
Best cursor sizes: 16×16→16×16, 32×32→32×32
Environment variable LANG: en_US.UTF-8
System property file.encoding: UTF-8
System property sun.jnu.encoding: UTF-8
Locale info: en_US
Numbers with default locale: 1234567890 -> 1234567890
Desktop environment: GNOME
VM arguments: [--add-opens=java.desktop/javax.swing.text.html=ALL-UNNAMED, -Djosm.restart=true]
Dataset consistency test: No problems found

Plugins:
+ ColorPlugin (v1.1.2.1)
+ ImproveWay (32)
+ Mapillary (2.1.1)
+ OpeningHoursEditor (35924)
+ PicLayer (1.0.2)
+ PolygonCutOut (v0.7)
+ Relation.Validation.Plugin (1.0.1)
+ RelationDissolve (0.2.0)
+ Review.Changes (1.0.5)
+ RoadSigns (36011)
+ SimplifyArea (35978)
+ apache-commons (36034)
+ apache-http (35924)
+ auto_tools (81)
+ centernode (v1.0.4)
+ conflation (0.6.9)
+ continuosDownload (105)
+ ejml (35924)
+ fastdriveway (v1.0.1)
+ geotools (36028)
+ jackson (36034)
+ jaxb (35952)
+ jna (36005)
+ josm-batch-downloader (1.0.4)
+ josm_magic_wand (1.1.0)
+ jts (36004)
+ markseen (14)
+ merge-overlap (35893)
+ notesolver (0.4.2)
+ opendata (36025)
+ openindoor-1.0.2-josm (UNKNOWN)
+ openqa (v0.3.3)
+ pdfimport (35976)
+ pt_assistant (1ff2e15)
+ rasterfilters (1.0.3)
+ reltoolbox (35976)
+ reverter (36043)
+ shrinkwrap (v1.0.4)
+ tageditor (36011)
+ todo (30306)
+ tofix (490)
+ turnlanes-tagging (v0.0.5)
+ turnrestrictions (36011)
+ utilsplugin2 (36011)
+ waydownloader (36011)
+ wikipedia (605)

Tagging presets:
+ https://josm.openstreetmap.de/josmfile?page=Presets/ParkingLanes&zip=1
+ C:\Users\cyron\AppData\Roaming\JOSM/EasyPresets.xml
+ <josm.userdata>/EasyPresets.xml

Map paint styles:
- https://josm.openstreetmap.de/josmfile?page=Styles/Enhanced_Lane_and_Road_Attributes&zip=1
- https://raw.githubusercontent.com/species/josm-preset-traffic_sign_direction/master/direction.mapcss
- https://josm.openstreetmap.de/josmfile?page=Styles/light_source&zip=1
- https://github.com/bastik/mapcss-tools/raw/osm/mapnik2mapcss/osm-results/mapnik.zip
- https://raw.githubusercontent.com/OpenNauticalChart/josm/master/BNIWR_MapCSS.mapcss
- https://raw.githubusercontent.com/OpenNauticalChart/josm/master/CEVNI_MapCSS.mapcss
- https://josm.openstreetmap.de/josmfile?page=Styles/LessObtrusiveNodes&zip=1
- https://pasharm.github.io/New_basic_style_for_JOSM/New_basic_style.mapcss
- https://raw.githubusercontent.com/yopaseopor/indoormap/master/indoormap-style.mapcss

Validator rules:
+ https://josm.openstreetmap.de/josmfile?page=Rules/GermanySpecific&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Rules/KeepRight&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Rules/OSMLint&zip=1
+ https://raw.githubusercontent.com/stefan-a-bauer/josm-validators/master/mtb.validator.mapcss
+ https://josm.openstreetmap.de/josmfile?page=Rules/PublicTransportGtfs&zip=1

Last errors/warnings:
- 00009.559 E: java.nio.file.NoSuchFileException: C:\Users\cyron\AppData\Roaming\JOSM/EasyPresets.xml
- 00009.560 E: C:\Users\cyron\AppData\Roaming\JOSM/EasyPresets.xml
- 00009.561 E: java.nio.file.NoSuchFileException: <josm.userdata>/EasyPresets.xml
- 00009.561 E: <josm.userdata>/EasyPresets.xml
- 00016.207 E: Failed to locate image 'bus.png'
- 00816.377 E: java.net.SocketTimeoutException: Read timed out
- 00981.339 E: Failed to locate image '[[Image(pond.png)]]'
- 00981.342 E: Failed to locate image '[[Image(oil-palm.png)]]'
- 01645.200 E: Handled by bug report queue: java.lang.NullPointerException: Cannot invoke "java.util.Collection.iterator()" because "objects" is null



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

Warning issued by: BugReportExceptionHandler#handleException

=== STACK TRACE ===
Thread: AWT-EventQueue-0 (37) of main
java.lang.NullPointerException: Cannot invoke "java.util.Collection.iterator()" because "objects" is null
	at org.openstreetmap.josm.command.ChangePropertyCommand.<init>(ChangePropertyCommand.java:110)
	at org.openstreetmap.josm.gui.dialogs.properties.TagEditHelper$EditTagDialog.performTagEdit(TagEditHelper.java:591)
	at org.openstreetmap.josm.gui.dialogs.properties.TagEditHelper.editTag(TagEditHelper.java:321)
	at org.openstreetmap.josm.gui.dialogs.properties.PropertiesDialog$MouseClickWatch.mouseClicked(PropertiesDialog.java:1125)
	at java.desktop/java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:278)
	at java.desktop/java.awt.Component.processMouseEvent(Component.java:6623)
	at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3398)
	at java.desktop/java.awt.Component.processEvent(Component.java:6385)
	at java.desktop/java.awt.Container.processEvent(Container.java:2266)
	at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:4995)
	at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2324)
	at java.desktop/java.awt.Component.dispatchEvent(Component.java:4827)
	at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4948)
	at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4584)
	at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4516)
	at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2310)
	at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2780)
	at java.desktop/java.awt.Component.dispatchEvent(Component.java:4827)
	at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:775)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:720)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:714)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:97)
	at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:747)
	at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
	at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
	at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:744)
	at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

[taylor.smock]

I think this should be a fairly easy fix. I'll see if I can write a non-regression test before I apply the patch though.

src/org/openstreetmap/josm/gui/dialogs/properties/TagEditHelper.java

@@ -113 +113 @@
     private final Map<String, Map<String, Integer>> valueCount;
 
     // Selection that we are editing by using both dialogs
-    protected Collection<OsmPrimitive> sel;
+    protected Collection<OsmPrimitive> sel = Collections.emptyList();
 
     private String changedKey;
 
@@ -415 +415 @@
      * @since 14509
      */
     public void resetSelection() {
-        sel = null;
+        sel = Collections.emptyList();
     }
 
     /**

[taylor.smock]

I have no clue how this actually happens though -- the only place our code calls resetSelection is when we change layers, and that should be called only from the EDT, so sel should never be null in JOSM core codepaths.

[taylor.smock]

Can you give us some idea of what you were doing when the crash happened? I can put in a workaround fairly easily, but something else is going on here.

For example:

• While using RelationDissolve and editing tags, this crash occurred.