Hello Lionel,
I have made a topic about a bug here : viewtopic.php?f=32&t=7187, but no one seams to have a clue.
For animation in Blender, it's handy - if not necessary - to have the main scene and the rigged characters in separated .blend files.
I don't know if you're familiar with this procedure, but it's done buy all character animators, I explain it briefly :
you place your environnement and set your camera in a main .blend, lets call it "main_set.blend"
From there you wanna call rigs and props, wich are stored in other blend files aside.
Lets say you have a complex rigged character : you group all of it (bones, armature, geometry) and call this group 'myrig'. you save this file in "my_character.blend".
Back to the master blend file (main_set.blend), you do file > link -> path to.../mycharacter.blend ->group-> 'myrig'.
The linked group is now available in main_set.blend via the command shift + A / group instance.
Currently, your exporter is lost and crashes if you have links / groups in it.
I have reproduced this bug context in the zipped files attached, If you'd have a moment to figure this out, it would be awesome.
The attached files contains the master scene (the default cube), and a .blend wich contains the rig to import as a linked group.
Exporter crashes, leaving an unfinished .obj , and blender's console says : "Runtime Error : Object does not have geometry data".
I'm at your service if you want help on testing stuffs about that.