Canceling prechaching tiles raise error

[xangel1@…]

What steps will reproduce the problem?

1. On layer tracks, choose precaching tiles
2. Choose tiling layer
3. Cancel precaching
4. Click on something at layers panel

What is the expected result?

Canceled operation and no error

What happens instead?

Everywhere i clicked raise that error

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: 2018-10-28 22:27:31 +0100 (Sun, 28 Oct 2018)
Build-Date:2018-10-28 21:33:32
Revision:14382
Relative:URL: ^/trunk

Identification: JOSM/1.5 (14382 ru) Linux Gentoo/Linux
Memory Usage: 893 MB / 1820 MB (315 MB allocated, but free)
Java version: 1.8.0_181-b13, Oracle Corporation, OpenJDK 64-Bit Server VM
Screen: :0.0 1920x1080
Maximum Screen Size: 1920x1080
Java package: icedtea-bin:!!! -e, --exact-name is now default.
!!! Use globbing to simulate the old behavior.

3.9.0-r1
VM arguments: [-Dicedtea-web.bin.name=itweb-javaws, -Dicedtea-web.bin.location=/usr/bin/itweb-javaws]
Dataset consistency test: No problems found

Plugins:
+ OpeningHoursEditor (34535)
+ apache-commons (34506)
+ buildings_tools (34572)
+ imagery_offset_db (34641)
+ jogl (1.2.2)
+ photo_geotagging (34576)
+ photoadjust (34684)
+ pt_assistant (v2.1.8)
+ reverter (34552)
+ wikipedia (v1.1.1)

Tagging presets:
+ https://raw.githubusercontent.com/yopaseopor/traffic_signs_preset_JOSM/master/RU.zip
+ https://raw.githubusercontent.com/ruosm-presets/literan-moscow/master/russian_shops.xml
+ https://josm.openstreetmap.de/josmfile?page=Presets/ParkingLanes&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/NewTags&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Addr2&zip=1
+ https://josm.openstreetmap.de/josmfile?page=Presets/Playground_Equipment&zip=1
+ http://zibi.openstreetmap.org.pl/kendzi/k/Simple3dPreset/s3db-preset.zip
+ https://josm.openstreetmap.de/josmfile?page=Presets/Surveillance&zip=1

Map paint styles:
+ https://josm.openstreetmap.de/josmfile?page=Styles/NewHighwayColors&zip=1
- https://www.openrailwaymap.org/styles/standard.zip
- https://github.com/bastik/mapcss-tools/raw/osm/mapnik2mapcss/osm-results/mapnik.zip
- https://josm.openstreetmap.de/josmfile?page=Styles/light_source&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/LitObjects&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/SimpleRoofTags&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/SimpleBuildingTags&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/ParkingLanes&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/PublicTransport&zip=1

Validator rules:
+ https://raw.githubusercontent.com/zetx16/Josm-HnumbValidator/master/ru-housenumber.validator.mapcss

Last errors/warnings:
- E: Handled by bug report queue: org.openstreetmap.josm.gui.progress.ProgressException: Expected states are [IN_TASK, IN_SUBTASK] but current state is FINISHED
- W: Too many errors. Dropping ReportedException [thread=Thread[Precache downloader,5,JOSM], exception=org.openstreetmap.josm.gui.progress.ProgressException: Expected states are [IN_TASK, IN_SUBTASK] but current state is FINISHED, methodWarningFrom=BugReportExceptionHandler#handleException]
- E: Handled by bug report queue: org.openstreetmap.josm.gui.progress.ProgressException: Expected states are [IN_TASK, IN_SUBTASK] but current state is FINISHED
- W: Too many errors. Dropping ReportedException [thread=Thread[Precache downloader,5,JOSM], exception=org.openstreetmap.josm.gui.progress.ProgressException: Expected states are [IN_TASK, IN_SUBTASK] but current state is FINISHED, methodWarningFrom=BugReportExceptionHandler#handleException]
- E: Handled by bug report queue: org.openstreetmap.josm.gui.progress.ProgressException: Expected states are [IN_TASK, IN_SUBTASK] but current state is FINISHED
- W: Too many errors. Dropping ReportedException [thread=Thread[Precache downloader,5,JOSM], exception=org.openstreetmap.josm.gui.progress.ProgressException: Expected states are [IN_TASK, IN_SUBTASK] but current state is FINISHED, methodWarningFrom=BugReportExceptionHandler#handleException]
- E: Handled by bug report queue: org.openstreetmap.josm.gui.progress.ProgressException: Expected states are [IN_TASK, IN_SUBTASK] but current state is FINISHED
- W: Too many errors. Dropping ReportedException [thread=Thread[Precache downloader,5,JOSM], exception=org.openstreetmap.josm.gui.progress.ProgressException: Expected states are [IN_TASK, IN_SUBTASK] but current state is FINISHED, methodWarningFrom=BugReportExceptionHandler#handleException]
- E: Handled by bug report queue: org.openstreetmap.josm.gui.progress.ProgressException: Expected states are [IN_TASK, IN_SUBTASK] but current state is FINISHED
- W: Too many errors. Dropping ReportedException [thread=Thread[Precache downloader,5,JOSM], exception=org.openstreetmap.josm.gui.progress.ProgressException: Expected states are [IN_TASK, IN_SUBTASK] but current state is FINISHED, methodWarningFrom=BugReportExceptionHandler#handleException]


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

Warning issued by: BugReportExceptionHandler#handleException

=== STACK TRACE ===
Thread: Precache downloader (1935)
org.openstreetmap.josm.gui.progress.ProgressException: Expected states are [IN_TASK, IN_SUBTASK] but current state is FINISHED
	at org.openstreetmap.josm.gui.progress.AbstractProgressMonitor.checkState(AbstractProgressMonitor.java:84)
	at org.openstreetmap.josm.gui.progress.AbstractProgressMonitor.internalUpdateProgress(AbstractProgressMonitor.java:266)
	at org.openstreetmap.josm.gui.progress.AbstractProgressMonitor.setTicks(AbstractProgressMonitor.java:244)
	at org.openstreetmap.josm.gui.progress.AbstractProgressMonitor.worked(AbstractProgressMonitor.java:258)
	at org.openstreetmap.josm.gui.layer.AbstractTileSourceLayer$PrecacheTask.tileLoadingFinished(AbstractTileSourceLayer.java:1815)
	at org.openstreetmap.josm.data.imagery.TMSCachedTileLoaderJob.loadingFinished(TMSCachedTileLoaderJob.java:203)
	at org.openstreetmap.josm.data.cache.JCSCachedTileLoaderJob.finishLoading(JCSCachedTileLoaderJob.java:265)
	at org.openstreetmap.josm.data.cache.JCSCachedTileLoaderJob.run(JCSCachedTileLoaderJob.java:232)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)

[wiktorn]

In 14427/josm:

Fix canceling precaching imageries along GPX track

• when GPX is big it was possibile to cancel task before precacheTask was set in

PrecacheWmsTask.realRun(). This caused NPE and prevented cleaning download
queue

• PrecacheTask.tileLoadingFinished updated progress monitor even if task was

already cancelled and this led to invalid state exception in ProgressMonitor,
as there are many download tasks run in parallel and we do not cancel them if
they already started. Now, after download is cancelled, no updates are issued

Closes: #16966