A grease pencil test file (can be found here: https://cloud.blender.org/p/gallery/5d9c6ee20f9018baaca071c3) was crashing when converting to GPv3. The index of a deform weight group was out of bounds. We will have to investgate how this can happen, but in the conversion code it seems best to ignore and skip over invalid indices. Pull Request: https://projects.blender.org/blender/blender/pulls/120170