the only symptom has been the actual flag popping up stating I ran into "an unexpected exception" - all that was done previously was looking at the Mapillary imagery from one camera to the other.

[anonymous]

What steps will reproduce the problem?

What is the expected result?

What happens instead?

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: 2021-04-27 20:35:33 +0200 (Tue, 27 Apr 2021)
Build-Date:2021-04-27 21:58:39
Revision:17833
Relative:URL: ^/trunk

Identification: JOSM/1.5 (17833 en) Mac OS X 10.15.7
OS Build number: Mac OS X 10.15.7 (19H524)
Memory Usage: 1698 MB / 1820 MB (554 MB allocated, but free)
Java version: 1.8.0_291-b10, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Look and Feel: com.apple.laf.AquaLookAndFeel
Screen: Display 69732992 1280×800 (scaling 1.00×1.00) Display 188956746 1920×1080 (scaling 1.00×1.00) Display 188956681 1920×1080 (scaling 1.00×1.00)
Maximum Screen Size: 1920×1080
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_US
Numbers with default locale: 1234567890 -> 1234567890
VM arguments: [-Djava.security.policy=file:<java.home>/lib/security/javaws.policy, -DtrustProxy=true, -Djnlpx.home=<java.home>/bin, -Djava.security.manager, -Djnlpx.origFilenameArg=${HOME}/Desktop/JOSM.jnlp, -Djnlpx.remove=false, -Dsun.awt.warmup=true, -Djava.util.Arrays.useLegacyMergeSort=true, -Djnlpx.heapsize=NULL,2048m, -Dmacosx.jnlpx.dock.name=JOSM, -Dmacosx.jnlpx.dock.icon=${HOME}/Library/Application Support/Oracle/Java/Deployment/cache/6.0/25/4c122699-1024438f.icns, -Djnlpx.jvm="<java.home>/bin/java"]
Dataset consistency test: No problems found

Plugins:
+ AddrInterpolation (35640)
+ ImproveWay (29)
+ Mapillary (1.5.37.6)
+ apache-commons (35524)
+ apache-http (35589)
+ auto_tools (73)
+ buildings_tools (35669)
+ conflation (0.6.6)
+ graphview (35640)
+ javafx-osx (35655)
+ jna (35662)
+ jts (35458)
+ log4j (35458)
+ markseen (14)
+ osm-obj-info (56)
+ reverter (35732)
+ rex (53)
+ routing (35640)
+ turnrestrictions (35640)
+ utilsplugin2 (35691)

Tagging presets:
+ https://raw.githubusercontent.com/yopaseopor/traffic_signs_preset_JOSM/master/AR.zip
+ ${HOME}/Downloads/Presets_LaneAttributes-preset.xml

Map paint styles:
- https://raw.githubusercontent.com/KaartGroup/Kaart-Styles/master/Sanitas_Paintstyle.mapcss 
- https://raw.githubusercontent.com/KaartGroup/Kaart-Styles/master/Overlapping%20Ways.mapcss
+ https://josm.openstreetmap.de/josmfile?page=Styles/Lane_and_Road_Attributes&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Styles/Coloured_Streets&zip=1
+ https://raw.githubusercontent.com/KaartGroup/Kaart-Styles/master/Kaart-Styles.mapcss
- ${HOME}/Downloads/Kaart Styles 3.1-2.mapcss
- https://josm.openstreetmap.de/josmfile?page=Styles/MapWithAI&zip=1

Validator rules:
+ https://raw.githubusercontent.com/KaartGroup/KaartValidator/master/kaart.validator.mapcss

Last errors/warnings:
- 22972.698 E: Unknown detection "object--traffic-sign"
- 22972.699 E: Unknown detection "object--traffic-sign"
- 22972.699 E: Unknown detection "object--traffic-sign"
- 22972.700 E: Unknown detection "object--traffic-sign"
- 23202.918 E: Unknown detection "object--traffic-sign--direction"
- 23202.922 E: Unknown detection "object--traffic-sign"
- 23202.928 E: Unknown detection "object--traffic-sign"
- 23202.929 E: Unknown detection "object--traffic-sign"
- 23203.227 E: Handled by bug report queue: java.lang.IllegalArgumentException
- 23212.692 E: Handled by bug report queue: java.lang.IllegalArgumentException



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

Warning issued by: BugReportExceptionHandler#handleException

=== STACK TRACE ===
Thread: AWT-EventQueue-2 (46) of javawsApplicationThreadGroup
java.lang.IllegalArgumentException
	at org.openstreetmap.josm.plugins.mapillary.data.image.MapillarySequence.next(MapillarySequence.java:156)
	at org.openstreetmap.josm.plugins.mapillary.data.image.MapillaryAbstractImage.next(MapillaryAbstractImage.java:267)
	at org.openstreetmap.josm.plugins.mapillary.gui.MapillaryMainDialog.updateImage(MapillaryMainDialog.java:431)
	at org.openstreetmap.josm.plugins.mapillary.gui.MapillaryMainDialog.updateImage(MapillaryMainDialog.java:395)
	at org.openstreetmap.josm.plugins.mapillary.mode.SelectMode.mouseMoved(SelectMode.java:125)
	at java.awt.AWTEventMulticaster.mouseMoved(AWTEventMulticaster.java:330)
	at java.awt.AWTEventMulticaster.mouseMoved(AWTEventMulticaster.java:329)
	at java.awt.Component.processMouseMotionEvent(Component.java:6584)
	at javax.swing.JComponent.processMouseMotionEvent(JComponent.java:3342)
	at java.awt.Component.processEvent(Component.java:6308)
	at java.awt.Container.processEvent(Container.java:2239)
	at java.awt.Component.dispatchEventImpl(Component.java:4889)
	at java.awt.Container.dispatchEventImpl(Container.java:2297)
	at java.awt.Component.dispatchEvent(Component.java:4711)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4904)
	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4548)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4476)
	at java.awt.Container.dispatchEventImpl(Container.java:2283)
	at java.awt.Window.dispatchEventImpl(Window.java:2746)
	at java.awt.Component.dispatchEvent(Component.java:4711)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
	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:74)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:84)
	at java.awt.EventQueue$4.run(EventQueue.java:733)
	at java.awt.EventQueue$4.run(EventQueue.java:731)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
	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)

[taylor.smock]

Closed as duplicate of #20623.
This code is (hopefully) going away soon. That depends upon #17177.