Combine Way ... Could not combine ways... highlight ends

[nwastra@…]

What steps will reproduce the problem?

1.
I have a dataset of waterways that we have explicit permission to use in OSM. I have converted to .osm file and I search, for example, "North Maria Creek intermittent inview" and JOSM selects all the many segments of the waterway, then I select "Tools>Combine Way" and often all works well and I am able to merge the selected now single waterway into my Data Layer for eventual upload into the OSM.
2.
Sometimes I get this message "Could not combine ways. They could not be merged into a single string of nodes"
This could be for many reasons, some of which are obvious, like an extra branch of the stream with a similar name, but some are difficult to solve like a quite small gap in the steam (a missing segment in the database).
I often need to zoom in close at the end of the selection and view the selected ways by scrolling slowly toward the other end to find a quite small gap in the waterway dataset that is preventing the "Combine Way" operation. This can be tedious in a long and winding waterway.
3.
There is no visual indication of where the problem may be until I scroll along the stream, sometimes many times until I zoom in close enough for the gap to be found, or other very short spur with the same name branching off, etc.

What is the expected result?

I would like the Combine Way tool to highlight the end nodes of all combined ways it was able to join so that I could more easily spot where the problems may be when the tool was unable to combine at particular sections.
The Validator highlights nodes in yellow where it has found problems and some visual effect like that would work well.
Another tool in JOSM, the relation editor, is able to visually show a gap in multipolygons and zoom to the problem and that saves a lot of time sorting problems.

What happens instead?

Just the error message.
I have attached a small dataset on which you can search for "North Maria Creek intermittent inview" and try to combine the ways using "Tools>Combine Way". Search from zoomed out far enough so that all the Creek can be searched.
This is an extreme example but other bigger ones are often hard to locate too on long ways.
I normally resolve difficult ones by combining a few ways at a time from one end until finding the problem and fixing.

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: 2019-07-10 00:52:47 +0200 (Wed, 10 Jul 2019)
Build-Date:2019-07-10 01:30:51
Revision:15238
Relative:URL: ^/trunk

Identification: JOSM/1.5 (15238 en_AU) Mac OS X 10.14.5
OS Build number: Mac OS X 10.14.5 (18F132)
Memory Usage: 1007 MB / 1820 MB (340 MB allocated, but free)
Java version: 1.8.0_211-b12, Oracle Corporation, Java HotSpot(TM) 64-Bit Server VM
Screen: Display 69951636 2048x1152
Maximum Screen Size: 2048x1152
VM arguments: [-Djava.library.path=/private/var/folders/z5/0092mtt52c5ckgm0blz8xz1w0000gp/T/AppTranslocation/4DCF8A8F-ABC0-47E7-93AC-8DB20FA8A16B/d/JOSM.app/Contents/MacOS, -DLibraryDirectory=${HOME}/Library, -DDocumentsDirectory=${HOME}/Documents, -DApplicationSupportDirectory=${HOME}/Library/Application Support, -DCachesDirectory=${HOME}/Library/Caches, -DApplicationDirectory=${HOME}/Applications, -DAutosavedInformationDirectory=${HOME}/Library/Autosave Information, -DDesktopDirectory=${HOME}/Desktop, -DDownloadsDirectory=${HOME}/Downloads, -DMoviesDirectory=${HOME}/Movies, -DMusicDirectory=${HOME}/Music, -DPicturesDirectory=${HOME}/Pictures, -DSharedPublicDirectory=${HOME}/Public, -DSystemLibraryDirectory=/Library, -DSystemApplicationSupportDirectory=/Library/Application Support, -DSystemCachesDirectory=/Library/Caches, -DSystemApplicationDirectory=/Applications, -DSystemUserDirectory=/Users, -DUserHome=${HOME}, -DSandboxEnabled=true, -DLaunchModifierFlags=0, -DLaunchModifierFlagCapsLock=false, -DLaunchModifierFlagShift=false, -DLaunchModifierFlagControl=false, -DLaunchModifierFlagOption=false, -DLaunchModifierFlagCommand=false, -DLaunchModifierFlagNumericPad=false, -DLaunchModifierFlagHelp=false, -DLaunchModifierFlagFunction=false, -Dapple.laf.useScreenMenuBar=true, -Dcom.apple.macos.use-file-dialog-packages=true, -Dcom.apple.macos.useScreenMenuBar=true, -Dcom.apple.mrj.application.apple.menu.about.name=JOSM, -Dcom.apple.smallTabs=true]

Dataset consistency test:
[WARN - NO NODES] Way {Way id=-4183661 version=0 VT> nodes=[{Node id=-3735666 version=0 V lat=-18.5125,lon=146.218645}]} has only one node
[WARN - NO NODES] Way {Way id=-4191062 version=0 VT> nodes=[{Node id=-4016104 version=0 V lat=-19.4375,lon=147.256461}]} has only one node
[WARN - NO NODES] Way {Way id=-4178947 version=0 VT> nodes=[{Node id=-3732812 version=0 V lat=-18.6425,lon=146.311244}]} has only one node
[WARN - NO NODES] Way {Way id=-4190036 version=0 VT> nodes=[{Node id=-3995946 version=0 V lat=-17.621082,lon=145.610000001}]} has only one node
[WARN - NO NODES] Way {Way id=-4192943 version=0 VT> nodes=[{Node id=-4093936 version=0 V lat=-16.953224,lon=145.7075}]} has only one node
[WARN - NO NODES] Way {Way id=-4192888 version=0 VT> nodes=[{Node id=-4092814 version=0 V lat=-17.6225,lon=145.56765}]} has only one node
[WARN - NO NODES] Way {Way id=-4186862 version=0 VT> nodes=[{Node id=-3925508 version=0 V lat=-17.718067,lon=145.725000001}]} has only one node
[WARN - NO NODES] Way {Way id=-4183915 version=0 VT> nodes=[{Node id=-3833258 version=0 V lat=-17.369005,lon=145.4525}]} has only one node
[WARN - NO NODES] Way {Way id=-4192765 version=0 VT> nodes=[{Node id=-4089766 version=0 V lat=-17.4133145,lon=145.4625}]} has only one node
[WARN - NO NODES] Way {Way id=-4188546 version=0 VT> nodes=[{Node id=-3963942 version=0 V lat=-16.9773125,lon=145.7225}]} has only one node
[WARN - NO NODES] Way {Way id=-4185705 version=0 VT> nodes=[{Node id=-3885856 version=0 V lat=-17.480000001,lon=145.479124001}]} has only one node


Plugins:
+ DirectUpload (35041)
+ FastDraw (34977)
+ ImproveWay (26)
+ InfoMode (34908)
+ Mapillary (1.5.18)
+ PicLayer (35030)
+ apache-commons (34908)
+ apache-http (34908)
+ conflation (0.6.3)
+ ejml (35049)
+ ext_tools (34988)
+ geojson (124)
+ geotools (34908)
+ graphview (34977)
+ jaxb (35014)
+ jna (34908)
+ jts (35064)
+ log4j (34908)
+ measurement (35051)
+ opendata (34997)
+ openvisible (34908)
+ pbf (35033)
+ pdfimport (34977)
+ reverter (34999)
+ rex (53)
+ routing (35039)
+ todo (30306)
+ turnrestrictions (34977)
+ utilsplugin2 (34977)

Map paint styles:
- https://josm.openstreetmap.de/josmfile?page=Styles/Cycleways&zip=1
- https://github.com/bastik/mapcss-tools/raw/osm/mapnik2mapcss/osm-results/mapnik.zip
- https://josm.openstreetmap.de/josmfile?page=Styles/Maxspeed&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Noname&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Lane_and_Road_Attributes&zip=1
- https://github.com/igitov/forest-josm-style/archive/master.zip
- https://josm.openstreetmap.de/josmfile?page=Styles/LessObtrusiveNodes&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Coloured_Suburb&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/light_source&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/sac_scale&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Sidewalks&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Noname&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/DestinationSignRelation&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Enhanced_Lane_and_Road_Attributes&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Lane_features&zip=1
- https://josm.openstreetmap.de/josmfile?page=Styles/Lane_features_ryg&zip=1

Last errors/warnings:
- W: No configuration settings found.  Using hardcoded default values for all pools.

[nwastra@…]

small sample .osm file plus a screen capture

[nwastra@…]

screenshot