Hello list

I'm getting the error below processing a tile from Vietnam:

Exception in thread "main" java.lang.AssertionError
       at uk.me.parabola.imgfmt.app.net.RoadIndex.write(RoadIndex.java:45)
       at uk.me.parabola.imgfmt.app.net.RoadDef.writeLevelDivs(RoadDef.java:356)
       at uk.me.parabola.imgfmt.app.net.RoadDef.writeNet1(RoadDef.java:237)
       at uk.me.parabola.imgfmt.app.net.NETFile.write(NETFile.java:68)
       at uk.me.parabola.mkgmap.build.MapBuilder.makeMap(MapBuilder.java:355)
       at uk.me.parabola.mkgmap.main.MapMaker.makeMap(MapMaker.java:114)
       at uk.me.parabola.mkgmap.main.MapMaker.makeMap(MapMaker.java:70)
       at uk.me.parabola.mkgmap.main.Main.lambda$processFilename$1(Main.java:291)
       at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
       at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor
.java:1128)
       at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecuto
r.java:628)
       at java.base/java.lang.Thread.run(Thread.java:829)

The simplest command triggering the error is: java -jar mkgmap.jar --route 51120021.o5m

Tile can be downloaded from https://alternativaslibres.org/tmp/51120021.o5m

My mkgmap version is 4907