NullPointerException on Overpass download with "out ids/tags center"

[martin@…]

What steps will reproduce the problem?

Download from Overpass with this query: "[out:json][bbox:{{bbox}}]; way; out ids center;"

• out:xml instead of out:json gives an explicit illegal data error instead
• node instead of way works fine
• Without center there is no error and the layer tooltip suggests nodes and ways were imported. Nothing is rendered which makes sense when no coordinates are returned.
• "out tags" behaves the same way as "out ids"

What is the expected result?

Probably one of:

1. Illegal data error like with out:xml
2. Same behaviour as without center

What happens instead?

NullPointerException as reported below. I have not seen any signs that the data or application state is broken after ignoring the exception.

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

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2023-05-01 18:25:03 +0200 (Mon, 01 May 2023)
Revision:18721
Build-Date:2023-05-02 01:30:57
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (18721 en_GB) Linux Fedora Linux 37 (KDE Plasma)
Memory Usage: 2836 MB / 8004 MB (498 MB allocated, but free)
Java version: 17.0.6+10, Red Hat, Inc., OpenJDK 64-Bit Server VM
Look and Feel: javax.swing.plaf.metal.MetalLookAndFeel
Screen: :0.0 3840×2160 (scaling 1.00×1.00)
Maximum Screen Size: 3840×2160
Best cursor sizes: 16×16→16×16, 32×32→32×32
Environment variable LANG: en_GB.UTF-8
System property file.encoding: UTF-8
System property sun.jnu.encoding: UTF-8
Locale info: en_GB
Numbers with default locale: 1234567890 -> 1234567890
Desktop environment: KDE
Java package: java-17-openjdk:x86_64-17.0.6.0.10
Dataset consistency test: No problems found

Plugins:
+ FastDraw (36057)
+ ImportImagePlugin (36013)
+ Mapillary (2.1.3)
+ OpeningHoursEditor (35924)
+ apache-commons (36034)
+ apache-http (35924)
+ areaselector (1652822522)
+ austriaaddresshelper (master-4e80dc2e4261d321150187f4951684ad97342d5e)
+ conflation (0.6.11)
+ editgpx (36054)
+ ejml (35924)
+ geotools (36068)
+ jackson (36034)
+ jaxb (35952)
+ jna (36005)
+ jogl (1.2.3)
+ jts (36004)
+ log4j (36034)
+ measurement (35978)
+ photo_geotagging (35933)
+ photoadjust (36011)
+ reverter (36043)
+ todo (123)
+ utilsplugin2 (36011)

Tagging presets:
+ https://github.com/yopaseopor/traffic_signs_preset_JOSM/raw/master/NO.zip
+ ${HOME}/src/josm_styles/ped_bike/sykkel-preset.xml
+ ${HOME}/src/josm_styles/ped_bike/gange-preset.xml

Map paint styles:
- https://raw.githubusercontent.com/JohanEntur/JohanEntur/main/otpWayPropertySets.mapcss
- https://osm.wzh.be/josm/different_buildings/different_buildings.mapcss
- ${HOME}/src/josm_styles/pedestrian_details.mapcss
- ${HOME}/src/josm_styles/ski_details.mapcss
- ${HOME}/src/josm_styles/missing_surface.mapcss
- ${HOME}/src/josm_styles/ped_bike/ped_bike.mapcss

Validator rules:
- ${HOME}/src/josm_styles/buildings-import.validator.mapcss
- ${HOME}/src/josm_styles/barnehage-import.validator.mapcss
- https://osm.wzh.be/josm/validation/advanced-power.validator.mapcss
- https://osm.wzh.be/josm/validation/buildings-import.validator.mapcss
- https://osm.wzh.be/josm/validation/wulfmorn.validator.mapcss
- ${HOME}/src/josm_styles/n50-hytter-import.validator.mapcss
- ${HOME}/src/josm_styles/pedestrian_details.validator.mapcss
+ ${HOME}/src/josm_styles/ped_bike/ped_bike.validator.mapcss
+ https://nyhus.dev/osm/josm/highest_quality.validator.mapcss

Last errors/warnings:
- 05107.766 E: Handled by bug report queue: java.lang.NullPointerException: Cannot invoke "javax.json.JsonArray.iterator()" because the return value of "javax.json.JsonObject.getJsonArray(String)" is null



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

Warning issued by: BugReportExceptionHandler#handleException

=== STACK TRACE ===
Thread: AWT-EventQueue-0 (29) of main
java.lang.NullPointerException: Cannot invoke "javax.json.JsonArray.iterator()" because the return value of "javax.json.JsonObject.getJsonArray(String)" is null
	at org.openstreetmap.josm.io.OsmJsonReader.readWayNodesAndTags(OsmJsonReader.java:150)
	at org.openstreetmap.josm.io.OsmJsonReader.lambda$parseWay$3(OsmJsonReader.java:146)
	at org.openstreetmap.josm.io.AbstractReader.parseWay(AbstractReader.java:725)
	at org.openstreetmap.josm.io.OsmJsonReader.parseWay(OsmJsonReader.java:146)
	at org.openstreetmap.josm.io.OsmJsonReader.parseElements(OsmJsonReader.java:88)
	at org.openstreetmap.josm.io.OsmJsonReader.parseRoot(OsmJsonReader.java:71)
	at org.openstreetmap.josm.io.OsmJsonReader.parse(OsmJsonReader.java:60)
	at org.openstreetmap.josm.io.OsmJsonReader.lambda$doParseDataSet$6(OsmJsonReader.java:187)
	at org.openstreetmap.josm.io.AbstractReader.doParseDataSet(AbstractReader.java:326)
	at org.openstreetmap.josm.io.AbstractReader.doParseDataSet(AbstractReader.java:309)
	at org.openstreetmap.josm.io.OsmJsonReader.doParseDataSet(OsmJsonReader.java:185)
	at org.openstreetmap.josm.io.OverpassDownloadReader.parseDataSet(OverpassDownloadReader.java:394)
	at org.openstreetmap.josm.io.BoundingBoxDownloader.parseOsm(BoundingBoxDownloader.java:215)
	at org.openstreetmap.josm.io.OverpassDownloadReader.parseOsm(OverpassDownloadReader.java:400)
	at org.openstreetmap.josm.actions.downloadtasks.DownloadOsmTask$DownloadTask.parseDataSet(DownloadOsmTask.java:469)
	at org.openstreetmap.josm.actions.downloadtasks.DownloadOsmTask$DownloadTask.realRun(DownloadOsmTask.java:477)
	at org.openstreetmap.josm.gui.PleaseWaitRunnable.doRealRun(PleaseWaitRunnable.java:94)
	at org.openstreetmap.josm.gui.PleaseWaitRunnable.run(PleaseWaitRunnable.java:142)
	at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
	at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
	at java.base/java.lang.Thread.run(Thread.java:833)

[mmd]

A few comments:

• JOSM needs XML format, so [out:json] cannot be used, as it produces OSM JSON format.
• out center; uses an (incompatible) Overpass API specific format extension for OSM XML. However, JOSM expects the original OSM XML format.

You can see the difference with ways:

  <way id="51005607">
    <center lat="40.5547721" lon="-5.1136667"/>       <!-- center is an Overpass API specific extension --->
  </way>

vs.

  <way id="51005607" version="15" timestamp="2023-05-01T13:51:29Z" changeset="135574988" uid="12166970" user="loborman">
    <nd ref="654172021"/>
    <nd ref="367109529"/>
    <nd ref="650358343"/>
[...]
    <nd ref="367109548"/>
    <tag k="highway" v="tertiary"/>
    <tag k="name" v="Calle Mayor"/>
    <tag k="old_name" v="Calle Calvo Sotelo"/>
    <tag k="oneway" v="no"/>
    <tag k="ref" v="N-110A"/>
    <tag k="surface" v="asphalt"/>
  </way>

Maybe JOSM could show a warning message or similar, if the query doesn't use out meta; . That's the only output mode which generates OSM data like the OSM API itself.

[martin@…]

OSM JSON works and is implemented in OsmJsonReader.java, however unlike readRelationMembersAndTags readWayNodesAndTags doesn't check for null after trying to read the nodes array. Based on a quick look at the code I suspect readWayNodesAndTags could check for null and throw an IllegalDataException, but I'm not certain enough to submit a patch. The XML parser handles ways without nodes, but that seems like more of an accidental implementation detail rather than a deliberate choice.