JOSM crashes when data contains way without nodes

[GerdP]

What steps will reproduce the problem?

1. load attached file
2. run validator
3. select way that produces the error "empty line" w43935619
4. Press Q (Orthogonalize Shape) or L (Align nodes) or R (Reverse way)

What is the expected result?

no action or maybe a warning that way has no nodes

What happens instead?

different crash reports

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

I've noticed that Multipolygon.joinWays() will loop forever when a way with 0 nodes is in the collection and wondered why nobody noticed this so far.
Not sure if this can be reproduced without manipulating an *.osm file in an editor like I did with the attached file.
No idea where this should be fixed.

Build-Date:2020-03-14 10:00:19
Revision:16117
Is-Local-Build:true

Identification: JOSM/1.5 (16117 SVN en) Windows 10 64-Bit
OS Build number: Windows 10 Home 1903 (18362)
Memory Usage: 686 MB / 1753 MB (261 MB allocated, but free)
Java version: 1.8.0_191-b12, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: \Display0 1920x1080
Maximum Screen Size: 1920x1080
VM arguments: [-agentlib:jdwp=transport=dt_socket,suspend=y,address=localhost:50962, -ea, -Dfile.encoding=UTF-8]
Program arguments: [--debug]

Dataset consistency test:
[WARN - ZERO NODES] Way {Way id=43935619 version=1 V nodes=[]} has zero nodes


Plugins:
+ OpeningHoursEditor (35250)
+ PolygonCutOut (v0.7)
+ apache-commons (35092)
+ buildings_tools (35248)
+ continuosDownload (91)
+ ejml (35122)
+ geotools (35169)
+ jaxb (35092)
+ jts (35122)
+ merge-overlap (35248)
+ o5m (35248)
+ opendata (35330)
+ pbf (35248)
+ poly (35248)
+ reverter (35313)
+ undelete (35313)
+ utilsplugin2 (35334)

Last errors/warnings:
- E: Handled by bug report queue: java.lang.NegativeArraySizeException
- E: Handled by bug report queue: java.lang.IllegalArgumentException: New way {Way id=43935619 version=1 V nodes=[]} has 0 nodes
- E: Handled by bug report queue: java.lang.NullPointerException
- E: Handled by bug report queue: java.lang.NullPointerException
- E: Handled by bug report queue: java.lang.NullPointerException
- E: Handled by bug report queue: java.lang.NullPointerException
- E: Handled by bug report queue: java.lang.NegativeArraySizeException
- E: Handled by bug report queue: java.lang.IllegalArgumentException: New way {Way id=43935619 version=1 V nodes=[]} has 0 nodes

[Don-vip]

In 16119/josm:

fix #18928 - fix various crashes with empty ways

[GerdP]

In 16134/josm:

see #18928: prevent possible endless loop in Multipolygon.joinWays()

[GerdP]

In 16135/josm:

see #18928: fix crash with empty way

[GerdP]

In 16136/josm:

see #18928: improve notification when empty way is used in Align nodes