NPE at MendRelationAction.backtrackCurrentEdge

[Polyglot]

What steps will reproduce the problem?

1. routing helper aborts with an error when the first way in a bicycle route relation is white when option 8 is selected

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: 2019-08-11 22:00:20 +0200 (Sun, 11 Aug 2019)
Build-Date:2019-08-12 01:30:56
Revision:15296
Relative:URL: ^/trunk

Identification: JOSM/1.5 (15296 fr) Linux Mint 18.3 Sylvia
Memory Usage: 1352 MB / 2711 MB (656 MB allocated, but free)
Java version: 1.8.0_191-8u191-b12-2ubuntu0.16.04.1-b12, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 1600x900
Maximum Screen Size: 1600x900
Java package: openjdk-8-jre:amd64-8u191-b12-2ubuntu0.16.04.1
libcommons-compress-java: libcommons-compress-java:-
libcommons-logging-java: libcommons-logging-java:all-1.2-1+build1
fonts-noto: fonts-noto:all-20160116-1
Dataset consistency test: No problems found

Plugins:
+ CustomizePublicTransportStop (35039)
+ Mapillary (1.5.18)
+ OpeningHoursEditor (34977)
+ PolygonCutOut (v0.7)
+ apache-commons (34908)
+ apache-http (34908)
+ buildings_tools (34982)
+ changeset-viewer (22)
+ ejml (35049)
+ geotools (34908)
+ graphview (34977)
+ jaxb (35014)
+ jna (34908)
+ jts (35064)
+ markseen (13)
+ measurement (35051)
+ opendata (34997)
+ pt_assistant (2.1.10-55-gd7fddae)
+ public_transport (34977)
+ scripting (30796)
+ tag2link (35043)
+ terracer (34977)
+ todo (30306)
+ utilsplugin2 (34977)
+ wikipedia (v1.1.1)

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

Map paint styles:
+ https://josm.openstreetmap.de/josmfile?page=Styles/NumberedCycleNodeNetworks&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/NumberedWalkingNodeNetworks&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Cycleways&zip=1
- ${HOME}/bus_stops_with_direction.mapcss
- ${HOME}/Fietssnelwegen Vlaanderen.mapcss
- https://raw.githubusercontent.com/yopaseopor/traffic_signs_style_JOSM/master/Styles_Traffic_signs_EUR.zip
- https://josm.openstreetmap.de/josmfile?page=Styles/MaxspeedIcons&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/PublicTransport&zip=1

Last errors/warnings:
- W: Mettre à jour - org.openstreetmap.josm.plugins.PluginHandler$UpdatePluginsMessagePanel[,0,0,0x0,invalid,layout=java.awt.GridBagLayout,alignmentX=0.0,alignmentY=0.0,border=,flags=9,maximumSize=,minimumSize=,preferredSize=]
- W: No configuration settings found.  Using hardcoded default values for all pools.
- E: Handled by bug report queue: java.lang.NullPointerException
- E: Thread main-worker-0 raised java.lang.NullPointerException
- E: Thread main-worker-0 raised java.lang.NullPointerException
- E: Thread main-worker-0 raised java.lang.NullPointerException
- E: Thread main-worker-0 raised java.lang.NullPointerException
- E: Thread main-worker-0 raised java.lang.NullPointerException
- W: The JSON response from the Wikidata Action API can't be decoded!: com.fasterxml.jackson.core.JsonParseException: Unexpected character ('<' (code 60)): expected a valid value (number, String, array, object, 'true', 'false' or 'null')
- 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 (16) of main
java.lang.NullPointerException
	at org.openstreetmap.josm.plugins.pt_assistant.actions.MendRelationAction.backtrackCurrentEdge(MendRelationAction.java:1563)
	at org.openstreetmap.josm.plugins.pt_assistant.actions.MendRelationAction$1.keyPressed(MendRelationAction.java:1443)
	at java.awt.Component.processKeyEvent(Component.java:6497)
	at javax.swing.JComponent.processKeyEvent(JComponent.java:2832)
	at java.awt.Component.processEvent(Component.java:6316)
	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.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1954)
	at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:835)
	at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1103)
	at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:974)
	at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:800)
	at java.awt.Component.dispatchEventImpl(Component.java:4760)
	at java.awt.Container.dispatchEventImpl(Container.java:2297)
	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)