Deleting conflation layer produces IllegalStateException

[Stereo]

What steps will reproduce the problem?

1. Conflate a natural park
2. Select all the layers
3. Hit delete

What is the expected result?

JOSM goes back to start screen

What happens instead?

IllegalStateException

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

Revision:17833
Build-Date:2021-04-27 22:16:42

Identification: JOSM/1.5 (17833 en_GB) Mac OS X 11.3
OS Build number: macOS 11.3 (20E232)
Memory Usage: 1504 MB / 4096 MB (258 MB allocated, but free)
Java version: 16.0.1+9, Azul Systems, Inc., OpenJDK 64-Bit Server VM
Look and Feel: com.apple.laf.AquaLookAndFeel
Screen: Display 69733632 1680×1050 (scaling 2.00×2.00)
Maximum Screen Size: 1680×1050
Best cursor sizes: 16×16→16×16, 32×32→32×32
System property file.encoding: UTF-8
System property sun.jnu.encoding: UTF-8
Locale info: en_GB
Numbers with default locale: 1234567890 -> 1234567890
VM arguments: [-Djpackage.app-version=17833, --add-exports=java.desktop/com.apple.eawt=ALL-UNNAMED, --add-exports=java.desktop/com.sun.imageio.plugins.jpeg=ALL-UNNAMED, --add-exports=java.desktop/com.sun.imageio.spi=ALL-UNNAMED, --add-opens=java.base/java.lang=ALL-UNNAMED, --add-opens=java.base/java.nio=ALL-UNNAMED, --add-opens=java.base/jdk.internal.loader=ALL-UNNAMED, --add-opens=java.base/jdk.internal.ref=ALL-UNNAMED, --add-opens=java.desktop/javax.imageio.spi=ALL-UNNAMED, --add-opens=java.desktop/javax.swing.text.html=ALL-UNNAMED, --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED, -Djpackage.app-path=/Applications/JOSM.app/Contents/MacOS/JOSM]
Dataset consistency test: No problems found

Plugins:
+ AddrInterpolation (35640)
+ CommandLine (35705)
+ Create_grid_of_ways (35640)
+ ImportImagePlugin (35567)
+ ImproveWay (29)
+ Mapillary (1.5.37.6)
+ OpeningHoursEditor (35640)
+ PicLayer (2a9aa7a)
+ RelationDissolve (0.2.0)
+ alignways (35640)
+ apache-commons (35524)
+ apache-http (35589)
+ areaselector (368)
+ austriaaddresshelper (1597341117)
+ auto_tools (73)
+ buildings_tools (35740)
+ changeset-viewer (25)
+ conflation (0.6.6)
+ continuosDownload (91)
+ contourmerge (v0.1.6)
+ ejml (35458)
+ flatlaf (35734)
+ geotools (35458)
+ gridify (1606242219)
+ http2 (35427)
+ imagery-xml-bounds (35723)
+ jaxb (35543)
+ jna (35662)
+ jogl (1.2.3)
+ jts (35458)
+ log4j (35458)
+ opendata (35640)
+ openqa (0.2.1)
+ poly (35640)
+ public_transport (35640)
+ reltoolbox (35640)
+ reverter (35732)
+ shrinkwrap (v1.0.4)
+ splinex (35718)
+ terracer (35640)
+ todo (30306)
+ undelete (35640)
+ utilsplugin2 (35691)
+ wikipedia (1.1.4)

Tagging presets:
+ https://josm.openstreetmap.de/josmfile?page=Presets/NewTags&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/BicycleJunction&preset&zip=1
+ http://osmtools.de/josm/steps.xml
+ https://josm.openstreetmap.de/josmfile?page=Presets/Historic_Stone&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/LaneAttributes&preset&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Golf_Course&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/PublicTransportOneClick&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Bus_lanes&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Historical_Objects&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/public_bookcase&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Stolpersteine&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/BuildingPreset&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Playground_Equipment&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/PublicTransportGtfs&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Heritage&zip=1
+ https://gitlab.com/k127/josm-presets/raw/master/diplomatic.xml

Map paint styles:
+ https://josm.openstreetmap.de/josmfile?page=Styles/Potlatch2&zip=1
- https://github.com/simon04/coloured-addresses.mapcss/raw/master/dist/coloured-addresses.mapcss
- https://josm.openstreetmap.de/josmfile?page=Styles/Coloured_Streets&style&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/HiDPISupport&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/AddressValidator&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Potlach2_access&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/iD&zip=1

Validator rules:
+ http://www.openrailwaymap.org/validator/openrailwaymap.validator.mapcss
+ https://josm.openstreetmap.de/josmfile?page=Rules/GermanySpecific&zip=1
+ http://www.openrailwaymap.org/validator/de-openrailwaymap.validator.mapcss
+ https://josm.openstreetmap.de/josmfile?page=Rules/MissingWeekdays&zip=1
+ https://raw.githubusercontent.com/nlehuby/transport_mapcss/master/transport.validator.mapcss

Last errors/warnings:
- 00621.210 W: java.net.http.HttpConnectTimeoutException: HTTP connect timed out. Cause: java.net.http.HttpConnectTimeoutException: HTTP connect timed out. Cause: java.net.ConnectException: HTTP connect timed out
- 00621.210 W: java.net.http.HttpConnectTimeoutException: HTTP connect timed out. Cause: java.net.http.HttpConnectTimeoutException: HTTP connect timed out. Cause: java.net.ConnectException: HTTP connect timed out
- 04806.581 W: restricted header name: "Connection"
- 04807.969 W: restricted header name: "Connection"
- 04808.262 W: restricted header name: "Connection"
- 05325.274 W: Simplify ways? - The selection contains 182 ways. Are you sure you want to simplify them all?
- 05865.212 W: restricted header name: "Connection"
- 05866.581 W: restricted header name: "Connection"
- 05866.979 W: restricted header name: "Connection"
- 08651.171 E: Handled by bug report queue: java.lang.IllegalStateException: The layer has already been destroyed: ConflationLayer [name=Conflation, associatedFile=null]



=== REPORTED CRASH DATA ===
LayerManager#fireLayerRemoving:
 - listener: org.openstreetmap.josm.gui.MapView[,0,0,1172x877,alignmentX=0.0,alignmentY=0.0,border=,flags=0,maximumSize=,minimumSize=java.awt.Dimension[width=10,height=0],preferredSize=]
 - event: LayerRemoveEvent [removedLayer=ConflationLayer [name=Conflation, associatedFile=null], lastLayer=false]
 - layer: ConflationLayer [name=Conflation, associatedFile=null]

BugReportExceptionHandler#handleException:
No data collected.

Warning issued by: BugReportExceptionHandler#handleException

=== STACK TRACE ===
Thread: AWT-EventQueue-0 (23) of main
java.lang.IllegalStateException: The layer has already been destroyed: ConflationLayer [name=Conflation, associatedFile=null]
	at org.openstreetmap.josm.gui.layer.Layer.destroy(Layer.java:288)
	at org.openstreetmap.josm.gui.MapView.layerRemoving(MapView.java:402)
	at org.openstreetmap.josm.gui.layer.LayerManager.fireLayerRemoving(LayerManager.java:476)
	at org.openstreetmap.josm.gui.layer.LayerManager.realRemoveSingleLayer(LayerManager.java:278)
	at org.openstreetmap.josm.gui.layer.MainLayerManager.realRemoveSingleLayer(MainLayerManager.java:307)
	at org.openstreetmap.josm.gui.layer.LayerManager.realRemoveLayer(LayerManager.java:266)
	at org.openstreetmap.josm.gui.layer.LayerManager.lambda$removeLayer$1(LayerManager.java:248)
	at org.openstreetmap.josm.gui.util.GuiHelper.runInEDTAndWaitWithException(GuiHelper.java:246)
	at org.openstreetmap.josm.gui.layer.LayerManager.removeLayer(LayerManager.java:248)
	at org.openstreetmap.josm.gui.dialogs.layer.DeleteLayerAction.actionPerformed(DeleteLayerAction.java:52)
	at java.desktop/javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
	at java.desktop/javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
	at java.desktop/javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
	at java.desktop/javax.swing.DefaultButtonModel.setPressed(Unknown Source)
	at java.desktop/javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
	at java.desktop/java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
	at java.desktop/java.awt.Component.processMouseEvent(Unknown Source)
	at java.desktop/javax.swing.JComponent.processMouseEvent(Unknown Source)
	at java.desktop/java.awt.Component.processEvent(Unknown Source)
	at java.desktop/java.awt.Container.processEvent(Unknown Source)
	at java.desktop/java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.desktop/java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.desktop/java.awt.Component.dispatchEvent(Unknown Source)
	at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
	at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
	at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
	at java.desktop/java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.desktop/java.awt.Window.dispatchEventImpl(Unknown Source)
	at java.desktop/java.awt.Component.dispatchEvent(Unknown Source)
	at java.desktop/java.awt.EventQueue.dispatchEventImpl(Unknown Source)
	at java.desktop/java.awt.EventQueue$4.run(Unknown Source)
	at java.desktop/java.awt.EventQueue$4.run(Unknown Source)
	at java.base/java.security.AccessController.doPrivileged(Unknown Source)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
	at java.desktop/java.awt.EventQueue$5.run(Unknown Source)
	at java.desktop/java.awt.EventQueue$5.run(Unknown Source)
	at java.base/java.security.AccessController.doPrivileged(Unknown Source)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
	at java.desktop/java.awt.EventQueue.dispatchEvent(Unknown Source)
	at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.desktop/java.awt.EventDispatchThread.run(Unknown Source)

[skyper]

Closed as duplicate of #16960.