Crash upon deleting and re-opening Mapillary imagery layer

[Traaker_L]

What steps will reproduce the problem?

1. Open the Mapillary layer from the Mapillary plugin.
2. Do some editing.
3. Delete the Mapillary layer, then re-open it.

What is the expected result?

The Mapillary layer appears in the editor

What happens instead?

The editor freezes completely after the "Downloading Mapillary images --- Select mode" message appears in the bottom-left corner. The Mapillary Images layer appears in the Layers list, but no images appear in the layer itself.

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

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2020-02-01 01:10:57 +0100 (Sat, 01 Feb 2020)
Revision:15806
Build-Date:2020-02-01 00:12:46
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (15806 en) Mac OS X 10.14.6
OS Build number: Mac OS X 10.14.6 (18G103)
Memory Usage: 1167 MB / 2048 MB (308 MB allocated, but free)
Java version: 11.0.5+10-LTS, Azul Systems, Inc., OpenJDK 64-Bit Server VM
Screen: Display 188945226 1920x1080, Display 69955240 2048x1152
Maximum Screen Size: 2048x1152
VM arguments: [--add-reads=java.base=ALL-UNNAMED,java.desktop, --add-reads=java.desktop=ALL-UNNAMED,java.naming, --add-reads=java.naming=ALL-UNNAMED,java.desktop, --add-exports=java.desktop/sun.awt=ALL-UNNAMED,java.desktop, --add-exports=java.desktop/javax.jnlp=ALL-UNNAMED,java.desktop, --add-exports=java.base/com.sun.net.ssl.internal.ssl=ALL-UNNAMED,java.desktop, --add-exports=java.base/sun.net.www.protocol.jar=ALL-UNNAMED,java.desktop, --add-exports=java.base/sun.security.action=ALL-UNNAMED,java.desktop, --add-exports=java.base/sun.security.provider=ALL-UNNAMED,java.desktop, --add-exports=java.base/sun.security.util=ALL-UNNAMED,java.desktop, --add-exports=java.base/sun.security.validator=ALL-UNNAMED,java.desktop, --add-exports=java.base/sun.security.x509=ALL-UNNAMED,java.desktop, --add-exports=java.base/jdk.internal.util.jar=ALL-UNNAMED,java.desktop, --add-exports=java.base/sun.net.www.protocol.http=ALL-UNNAMED,java.desktop, --add-exports=java.desktop/sun.awt.X11=ALL-UNNAMED,java.desktop, --add-exports=java.desktop/sun.applet=ALL-UNNAMED,java.desktop, --add-exports=java.desktop/sun.applet=ALL-UNNAMED,jdk.jsobject, --add-exports=java.naming/com.sun.jndi.toolkit.url=ALL-UNNAMED,java.desktop]
Dataset consistency test: No problems found

Plugins:
+ EasyPresets (1537621333)
+ Mapillary (1.5.20)
+ apache-commons (35092)
+ apache-http (35092)
+ auto_tools (73)
+ buildings_tools (35248)
+ graphview (35313)
+ intersection (0.0.7)
+ jna (35092)
+ osm-obj-info (56)
+ rex (53)
+ turnrestrictions (35313)
+ utilsplugin2 (35248)

Tagging presets:
+ https://raw.githubusercontent.com/osmlab/name-suggestion-index/master/dist/name-suggestions.presets.xml

Map paint styles:
+ https://raw.githubusercontent.com/KaartGroup/Kaart-Styles/master/Kaart-Styles.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

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

Last errors/warnings:
- W: No configuration settings found.  Using hardcoded default values for all pools.
- W: Region [userProfile_BLOCK_v2]  Problem verifying disk.
- W: Region [userProfile_BLOCK_v2] Resetting cache
- W: Could not read from URL https://a.mapillary.com/v3/image_detections?client_id=T1Fzd20xZjdtR0s1VDk5OFNIOXpYdzoxNDYyOGRkYzUyYTFiMzgz&bbox=101.6978645%2C3.102978%2C101.7051172%2C3.1130483&layers=trafficsigns&sort_by=key!: java.io.IOException: Server returned HTTP response code: 504 for URL: https://a.mapillary.com/v3/image_detections?client_id=T1Fzd20xZjdtR0s1VDk5OFNIOXpYdzoxNDYyOGRkYzUyYTFiMzgz&bbox=101.6978645%2C3.102978%2C101.7051172%2C3.1130483&layers=trafficsigns&sort_by=key
- W: Could not read from URL https://a.mapillary.com/v3/image_detections?layers=trafficsigns&client_id=T1Fzd20xZjdtR0s1VDk5OFNIOXpYdzoxNDYyOGRkYzUyYTFiMzgz&_next_page_token=eyJpZCI6IjFBTm9RMjFEaXREUGtYdlZCUEJQN1EiLCJhZnRlciI6WyIxQTV1SVBscEU0Q0RNaEFxQzFYUHlKIl0sIm9mZnNldCI6MX0%3D&sort_by=key&bbox=101.6946888%2C3.0991213%2C101.7051172%2C3.1130483!: java.io.IOException: Server returned HTTP response code: 504 for URL: https://a.mapillary.com/v3/image_detections?layers=trafficsigns&client_id=T1Fzd20xZjdtR0s1VDk5OFNIOXpYdzoxNDYyOGRkYzUyYTFiMzgz&_next_page_token=eyJpZCI6IjFBTm9RMjFEaXREUGtYdlZCUEJQN1EiLCJhZnRlciI6WyIxQTV1SVBscEU0Q0RNaEFxQzFYUHlKIl0sIm9mZnNldCI6MX0%3D&sort_by=key&bbox=101.6946888%2C3.0991213%2C101.7051172%2C3.1130483
- W: Unable to delete archived backup file <josm.userdata>/autosave/deleted_layers/Data Layer 3_20200211_142640930.osm
- W: Could not read from URL https://a.mapillary.com/v3/image_detections?layers=trafficsigns&client_id=T1Fzd20xZjdtR0s1VDk5OFNIOXpYdzoxNDYyOGRkYzUyYTFiMzgz&sort_by=key&_next_page_token=eyJhZnRlciI6WyI0R3ExZ0d1SHFUdlZwalVudmpYMWVZIl0sIm9mZnNldCI6MH0%3D&bbox=101.7091513%2C3.1318602%2C101.7190647%2C3.1400019!: java.io.IOException: Server returned HTTP response code: 504 for URL: https://a.mapillary.com/v3/image_detections?layers=trafficsigns&client_id=T1Fzd20xZjdtR0s1VDk5OFNIOXpYdzoxNDYyOGRkYzUyYTFiMzgz&sort_by=key&_next_page_token=eyJhZnRlciI6WyI0R3ExZ0d1SHFUdlZwalVudmpYMWVZIl0sIm9mZnNldCI6MH0%3D&bbox=101.7091513%2C3.1318602%2C101.7190647%2C3.1400019
- W: Could not read from URL https://a.mapillary.com/v3/images?client_id=T1Fzd20xZjdtR0s1VDk5OFNIOXpYdzoxNDYyOGRkYzUyYTFiMzgz&_next_page_token=eyJhZnRlciI6WzE1NzkyMzYxNDEwOTAsIjEzMUh3cE91WnRBcnI5dmJ3SUg1UFkiXX0%3D&bbox=101.7091513%2C3.1318602%2C101.7190647%2C3.1400019!: java.io.IOException: Server returned HTTP response code: 504 for URL: https://a.mapillary.com/v3/images?client_id=T1Fzd20xZjdtR0s1VDk5OFNIOXpYdzoxNDYyOGRkYzUyYTFiMzgz&_next_page_token=eyJhZnRlciI6WzE1NzkyMzYxNDEwOTAsIjEzMUh3cE91WnRBcnI5dmJ3SUg1UFkiXX0%3D&bbox=101.7091513%2C3.1318602%2C101.7190647%2C3.1400019
- W: Could not read from URL https://a.mapillary.com/v3/image_detections?layers=trafficsigns&client_id=T1Fzd20xZjdtR0s1VDk5OFNIOXpYdzoxNDYyOGRkYzUyYTFiMzgz&_next_page_token=eyJhZnRlciI6WyJQZUpNRjl3NkdQNG41MHZCYlhWQ2NLIl0sIm9mZnNldCI6MH0%3D&sort_by=key&bbox=101.7091942%2C3.1331886%2C101.7182493%2C3.1399162!: java.io.IOException: Server returned HTTP response code: 504 for URL: https://a.mapillary.com/v3/image_detections?layers=trafficsigns&client_id=T1Fzd20xZjdtR0s1VDk5OFNIOXpYdzoxNDYyOGRkYzUyYTFiMzgz&_next_page_token=eyJhZnRlciI6WyJQZUpNRjl3NkdQNG41MHZCYlhWQ2NLIl0sIm9mZnNldCI6MH0%3D&sort_by=key&bbox=101.7091942%2C3.1331886%2C101.7182493%2C3.1399162