If textures is packed inside blend file, then exporter will fail

[NikolaiVChr]

If textures is packed inside blend file, then exporter will fail.

This happens when trying to fetch filepath from texture_slot.texture.image

If I figure out how to fix it, I will.

[NikolaiVChr]

This is now fixed in https://github.com/NikolaiVChr/Blender-AC3D if someone would accept the pull request, that would be nice.