ValueError, when exporting an armature, that is not in the root, with collapse armatures enabled

[StjerneIdioten]

In LXML elements can only have one parent, where in Element Tree they can belong to multiple. The exporter manually deletes elements after moving them to a different parent during skinned mesh export (when collapsing armature nodes), but if using LXML this will crash since it has already been moved by LXML itself. This will only happen if the armature to be exported is not a root node itself.

[StjerneIdioten]

It seems to only be a problem if accidentally also selecting the armature itself (So a child of the root object), as when this happens using other object types the exporter merely duplicates the item. But for collapsed armature notes it crashes the exporter. So this seems more like a case of a badly handled "unexpected" user input.