Changing colour on GPX markers layer generates exception

[alester]

What steps will reproduce the problem?

1. Open a GPX file containing waypoints
2. Right-click on the "Markers from..." GPX file layer and select "Customize color"
3. Select a colour and click OK

What is the expected result?

The colour of the markers should be changed

What happens instead?

An exception dialog is displayed. After closing the dialog and changing zoom level, the colour change does take effect.

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

If it makes any difference, the GPX file was created on a Garmin Oregon 700 device.

URL:https://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2021-06-02 22:03:39 +0200 (Wed, 02 Jun 2021)
Build-Date:2021-06-02 20:11:30
Revision:17919
Relative:URL: ^/trunk

Identification: JOSM/1.5 (17919 en) Windows 10 64-Bit
OS Build number: Windows 10 Pro 2004 (19041)
Memory Usage: 638 MB / 7282 MB (345 MB allocated, but free)
Java version: 1.8.0_291-b10, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Look and Feel: com.sun.java.swing.plaf.windows.WindowsLookAndFeel
Screen: \Display0 1920×1080 (scaling 1.00×1.00) \Display1 1920×1080 (scaling 1.00×1.00)
Maximum Screen Size: 1920×1080
Best cursor sizes: 16×16→32×32, 32×32→32×32
System property file.encoding: Cp1252
System property sun.jnu.encoding: Cp1252
Locale info: en_US
Numbers with default locale: 1234567890 -> 1234567890

Plugins:
+ FixAddresses (35640)
+ ImportImagePlugin (35567)
+ PicLayer (1.0.1)
+ apache-commons (35524)
+ canvec_helper (35458)
+ ejml (35458)
+ geotools (35458)
+ jaxb (35543)
+ jogl (1.2.3)
+ jts (35458)
+ log4j (35458)
+ measurement (35640)
+ opendata (35640)
+ pbf (35720)
+ poly (35640)
+ reltoolbox (35640)
+ reverter (35732)
+ routing (35640)
+ terracer (35640)
+ todo (30306)
+ turnrestrictions (35640)
+ utilsplugin2 (35691)

Tagging presets:
+ https://josm.openstreetmap.de/josmfile?page=Presets/OneClick&zip=1

Map paint styles:
+ https://josm.openstreetmap.de/josmfile?page=Styles/Maxspeed&zip=1

Last errors/warnings:
- 00094.907 E: Failed to locate image 'Block, Green'
- 00094.908 E: Failed to locate image 'Flag, Blue'
- 00094.908 E: Failed to locate image 'Block, Green'
- 00094.909 E: Failed to locate image 'Block, Green'
- 00094.910 E: Failed to locate image 'Block, Green'
- 00094.911 E: Failed to locate image 'Block, Green'
- 00094.912 E: Failed to locate image 'Block, Green'
- 00094.914 E: Failed to locate image 'Block, Green'
- 00094.915 E: Failed to locate image 'Block, Green'
- 00100.669 E: Handled by bug report queue: java.lang.NullPointerException



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

Warning issued by: BugReportExceptionHandler#handleException

=== STACK TRACE ===
Thread: AWT-EventQueue-0 (19) of main
java.lang.NullPointerException
	at org.openstreetmap.josm.gui.preferences.display.GPXSettingsPanel.putLayerPrefLocal(GPXSettingsPanel.java:268)
	at org.openstreetmap.josm.gui.preferences.display.GPXSettingsPanel.putLayerPrefLocal(GPXSettingsPanel.java:254)
	at org.openstreetmap.josm.gui.layer.markerlayer.MarkerLayer.setColor(MarkerLayer.java:483)
	at org.openstreetmap.josm.gui.layer.CustomizeColor.lambda$actionPerformed$0(CustomizeColor.java:87)
	at java.util.ArrayList.forEach(Unknown Source)
	at org.openstreetmap.josm.gui.layer.CustomizeColor.actionPerformed(CustomizeColor.java:87)
	at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
	at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
	at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
	at javax.swing.AbstractButton.doClick(Unknown Source)
	at javax.swing.plaf.basic.BasicMenuItemUI.doClick(Unknown Source)
	at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(Unknown Source)
	at java.awt.Component.processMouseEvent(Unknown Source)
	at javax.swing.JComponent.processMouseEvent(Unknown Source)
	at java.awt.Component.processEvent(Unknown Source)
	at java.awt.Container.processEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Window.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
	at java.awt.EventQueue.access$500(Unknown Source)
	at java.awt.EventQueue$3.run(Unknown Source)
	at java.awt.EventQueue$3.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue$4.run(Unknown Source)
	at java.awt.EventQueue$4.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(Unknown Source)
	at java.awt.EventQueue.dispatchEvent(Unknown Source)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.run(Unknown Source)