Any idea what is going wrong here?

I think the result is actually okay...

Command:

C:\openmtbmap\maps>start /belownormal /b /wait java -jar -XX:+AggressiveHeap -XX:StringTableSize=1000003 -Xmx43000M C:\openmtbmap\mkgmap.jar --max-jobs=12 --order-by-decreasing-area --code-page=65001 "--style-file=C:\openmtbmap\buildings_style"  --lower-case --levels="0:24, 1:23, 2:22, 3:21" --ignore-osm-bounds --ignore-turn-restrictions --merge-lines --allow-reverse-merge --transparent --draw-priority=28 --remove-ovm-work-files=true --add-pois-to-areas --simplify-polygons=23:4,22:7,21:8 --copyright-file="C:\openmtbmap\openmtbmap_svn\copyrightopm.txt" --license-file="C:\openmtbmap\openmtbmap_svn\licenseopm.txt" --add-boundary-nodes-at-admin-boundaries=2 --poi-excl-index=0x6405,0x4316,0x2f00 --ignore-fixme-values --polygon-size-limits="24:16, 23:14, 22:12, 21:11" --ignore-turn-restrictions --description=velobuildings_eu --remove-ovm-work-files= --country-abbr=eu --country-name=europe --mapname=86900310 --family-id=8690 --product-id=1 --series-name="buildings_europe_09.12.2021_UC_LOCAL" --keep-going --family-name="velobuildings_eu_09.12.2021_UC_LOCAL" --tdbfile --x-gmapi-minimal --gmapsupp --overview-mapname=mapsetb --area-name="europe_09.12.2021_UC_LOCAL_buildings" -c D:\openmtbmap\maps\template.europeb1 8690*.img buildeu.typ  1>NUL

Mkgmap version 4827M
Time started: Thu Dec 09 12:50:49 CET 2021
Number of MapFailedExceptions: 0
SEVERE (OverviewBuilder): Tile selection (0x4a) polygon for tile 86900000 cannot be written in level 0 resolution 21, using 19 instead

........

skipped here

.......

gmapi-minimal: Skipping file 86900308.img
gmapi-minimal: Skipping file 86900309.img
gmapi-minimal: Writing freshly compiled file C:\openmtbmap\maps\.\86900310.img
gmapi-minimal: Writing freshly compiled file C:\openmtbmap\maps\.\86900311.img
Exception in thread "main" java.lang.ArithmeticException: / by zero
        at uk.me.parabola.imgfmt.sys.FileNode.write(FileNode.java:239)
        at uk.me.parabola.imgfmt.app.BufferedImgFileWriter.sync(BufferedImgFileWriter.java:77)
        at uk.me.parabola.imgfmt.app.BufferedImgFileWriter.close(BufferedImgFileWriter.java:106)
        at uk.me.parabola.imgfmt.sys.FileNode.close(FileNode.java:107)
        at uk.me.parabola.imgfmt.sys.ImgFS.sync(ImgFS.java:253)
        at uk.me.parabola.imgfmt.sys.ImgFS.close(ImgFS.java:325)
        at uk.me.parabola.imgfmt.Utils.closeFile(Utils.java:191)
        at uk.me.parabola.mkgmap.combiners.GmapsuppBuilder.onFinish(GmapsuppBuilder.java:187)
        at uk.me.parabola.mkgmap.main.Main.endOptions(Main.java:690)
        at uk.me.parabola.mkgmap.CommandArgsReader.readArgs(CommandArgsReader.java:126)
        at uk.me.parabola.mkgmap.main.Main.mainStart(Main.java:147)
        at uk.me.parabola.mkgmap.main.Main.main(Main.java:118)
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