[Bug] I3S to 3DTiles converter: TypeError: Cannot read properties of undefined (reading '0')

[AVK636]

Loader

tile-converter

Description

When trying to convert I3S/SLPK data from the open geo data portal of the german state North Rhine-Westphalia into 3DTiles, the converter crashes with the following outpout:

Input tileset value: Mesh_1409T12_nw_2023.slpk
Modified tileset value: Mesh_1409T12_nw_2023.slpk
------------------------------------------------
Starting conversion of I3S
------------------------------------------------
Loading egm file...
(node:70594) [DEP0040] DeprecationWarning: The `punycode` module is deprecated. Please use a userland alternative instead.
(Use `node --trace-deprecation ...` to show where the warning was created)
Loading egm file completed!
Analyze source layer
------------------------------------------------
Preprocess results:
Node count: 454030
------------------------------------------------
Node conversion: 42841
TypeError: Cannot read properties of undefined (reading '0')
    at Z.add (/home/AVK636/miniforge3/envs/gis2pcd/lib/node_modules/@loaders.gl/tile-converter/dist/converter.min.cjs:160:122929)
    at aD._normalizePositions (/home/AVK636/miniforge3/envs/gis2pcd/lib/node_modules/@loaders.gl/tile-converter/dist/converter.min.cjs:160:460291)
    at aD.buildGLTF (/home/AVK636/miniforge3/envs/gis2pcd/lib/node_modules/@loaders.gl/tile-converter/dist/converter.min.cjs:160:458328)
    at async aD.convert (/home/AVK636/miniforge3/envs/gis2pcd/lib/node_modules/@loaders.gl/tile-converter/dist/converter.min.cjs:160:457515)
    at async Ev.convertChildNode (/home/AVK636/miniforge3/envs/gis2pcd/lib/node_modules/@loaders.gl/tile-converter/dist/converter.min.cjs:160:466487)
    at async Ev._addChildren (/home/AVK636/miniforge3/envs/gis2pcd/lib/node_modules/@loaders.gl/tile-converter/dist/converter.min.cjs:160:467194)
    at async Ev.convert (/home/AVK636/miniforge3/envs/gis2pcd/lib/node_modules/@loaders.gl/tile-converter/dist/converter.min.cjs:160:464798)
    at async _It (/home/AVK636/miniforge3/envs/gis2pcd/lib/node_modules/@loaders.gl/tile-converter/dist/converter.min.cjs:160:475511)
    at async yIt (/home/AVK636/miniforge3/envs/gis2pcd/lib/node_modules/@loaders.gl/tile-converter/dist/converter.min.cjs:160:472770)

Expected Behavior

The program converts the I3S file into a 3DTiles file without errors.

Steps to Reproduce

1. Download a .slpk file from the open geo data portal (e.g. Mesh_1431T4Sued_nw_2024.slpk)
2. Run npx tile-converter --input-type I3S --tileset Mesh_1409T12_nw_2023.slpk --name test
3. Get the error mentioned above

Environment

• Framework version: loaders.gl@4.3.4
• Node: 22.13.0
• OS: Ubuntu 22.04

Logs

No response