Merge meshes of an gltf or glb

Hey guys, I was trying to load a gltf file and merge the meshes.
Loading is complete but the merge throws an error in console: “Uncaught (in promise) Error: Positions are required”
This is the demo: Babylon.js Playground
I appreciate any help, link on documentation etc.
Thank you

Hello and welcome!

This is because all meshes are not with geometry:

Cool thank you for the support!
I’ve obtained this gltf converting an obj file with obj2gltf. As with merging of obj meshes I had non issues I was expecting the same for gltf file