Unable to finish merging two layers

[aubreybachant@…]

Even with two extremely small layers (<10 nodes each).
It never manages to merge the two layers. It just stays loading for hours.

What steps will reproduce the problem?

1. Merge two layers together.

What is the expected result?

What happens instead?

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

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2023-08-29 13:38:40 +0200 (Tue, 29 Aug 2023)
Revision:18822
Build-Date:2023-08-30 01:30:57
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (18822 en) Mac OS X 14.0
OS Build number: macOS 14.0 (23A344)
Memory Usage: 937 MB / 2048 MB (331 MB allocated, but free)
Java version: 17.0.7+7-LTS, Azul Systems, Inc., OpenJDK 64-Bit Server VM
Look and Feel: com.apple.laf.AquaLookAndFeel
Screen: Display 1 1440×900 (scaling 2.00×2.00)
Maximum Screen Size: 1440×900
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
Dataset consistency test: No problems found

Plugins:
+ FastDraw (36126)
+ apache-commons (36034)
+ apache-http (35924)
+ auto_tools (81)
+ centernode (v1.0.4)
+ gridify (1606242219)
+ jaxb (36118)
+ jna (36126)
+ jogl (1.2.3)
+ kendzi3d (1.0.205)
+ kendzi3d-resources (0.0.2)
+ log4j (36045)
+ mapwithai (816)
+ mapwithai-dev (1.8.3-9-g16feefa)
+ measurement (36126)
+ pmtiles (36125)
+ splinex (36126)
+ terracer (36126)
+ utilsplugin2 (36134)

Map paint styles:
- https://josm.openstreetmap.de/josmfile?page=Styles/ColorWays&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Enhanced_Lane_and_Road_Attributes&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Surface&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/SimpleBuildingTags&zip=1
- https://github.com/bastik/mapcss-tools/raw/osm/mapnik2mapcss/osm-results/mapnik.zip
- https://josm.openstreetmap.de/josmfile?page=Styles/MapWithAI&zip=1
- https://pasharm.github.io/New_basic_style_for_JOSM/New_basic_style.mapcss

Last errors/warnings:
- 00009.788 E: Failed to locate image 'MapWithAI'
- 00009.973 W: java.lang.IllegalArgumentException: Even number of doubles expected in string, got 1: AE
- 00010.129 W: java.util.concurrent.ExecutionException: java.lang.ClassCastException. Cause: java.lang.ClassCastException. Cause: java.lang.ClassCastException: class javax.json.JsonValueImpl cannot be cast to class javax.json.JsonString (javax.json.JsonValueImpl and javax.json.JsonString are in unnamed module of loader 'app')
- 00010.136 W: java.util.concurrent.ExecutionException: java.lang.ClassCastException. Cause: java.lang.ClassCastException. Cause: java.lang.ClassCastException: class javax.json.JsonValueImpl cannot be cast to class javax.json.JsonString (javax.json.JsonValueImpl and javax.json.JsonString are in unnamed module of loader 'app')
- 00010.241 W: java.util.concurrent.ExecutionException: java.lang.ClassCastException. Cause: java.lang.ClassCastException. Cause: java.lang.ClassCastException: class javax.json.JsonValueImpl cannot be cast to class javax.json.JsonString (javax.json.JsonValueImpl and javax.json.JsonString are in unnamed module of loader 'app')
- 00010.244 W: java.util.concurrent.ExecutionException: java.lang.ClassCastException. Cause: java.lang.ClassCastException. Cause: java.lang.ClassCastException: class javax.json.JsonValueImpl cannot be cast to class javax.json.JsonString (javax.json.JsonValueImpl and javax.json.JsonString are in unnamed module of loader 'app')
- 00533.901 E: Thread main-worker-0 raised java.lang.IllegalStateException: Already registered a conflict for primitive '{Node id=811502313 version=1 MVD lat=38.9381953,lon=-77.0416586}'.

[gaben]

Merging works without issues for me, it's probably an edge case which I was unable to reproduce based on the available information.

Could you please attach the test dataset?