[QSRlib-core] `Object_State.return_bounding_box_2d` is broken when width or length are nan

[gatsoulis]

Object_State.return_bounding_box_2d in world_trace.py is broken when width or length are nan, as it returns nan-bounding boxes and since the qsrs (RCCs in particular) have no check they return non-sense QSRs.