Cannot export scene with KTX2 compressed model

[axekan]

Steps to reproduce:

1. Visit https://modelviewer.dev/editor/
2. Upload a model with ktx2-compressed textures
3. Click "Download Scene"
4. See error in console:

Uncaught (in promise) glTF export failed

Example model file compressed using gltfpack: ash_tree_ktx2.zip

Compressed using this command:

gltfpack -i ash_tree.glb -o ash_tree_ktx2.glb -tc

Original uncompressed model: ash_tree.zip