Broken: 2.83, 2.90.0, Commit date: 2020-08-24 16:27, Hash 1bced5884c3d
- Open main.blend
- On the selected Cube, make its material local
source/blender/blenkernel/intern/lib_id.c:117:69: runtime error: member access within null pointer of type 'struct Library'
Full backtrace: P1602
Issue goes away if
-  you delete Plane in the main file [linked -- also uses ani_matGlass_v09], save and reopen, ani_matGlass_v09 is then single-user on Cube, make local then works.
- or  in the src file you delete those two OSL shader nodes from ani_matGlass_v09: