Code would access invalid (null) `pchan->bone` pointers, presumably due
to the (linked) armature data being heavily modified compared to the
local Object's poses? At least that's the idea of what caused this
invalid state of pose data.
Unfortunately the issue was detected in a very complex case.
Essentially, opening an older snapshot (r3034) of a Pets production anim
file with assets from current repository r3055), which have been heavily
cleaned-up.
This triggers massive amount of missing linked data from the older anim
file, and extremely heavy resyncing process of liboverrides.
In any case, calling `BKE_pose_ensure` before accessing object's pose
data should never be a bad thing. ;)
fc02d5ee11