The original report stumbled upon this issue with a more tricky
configuration when light linking is combined with light tress.
However, the actual contributing factor was a mesh with emission
shader which is not assigned to any triangles. This triggered a
bug in the BoundBox::transformed() which converted non-valid bounds
to bounds by performing per-corner growing.
Additionally fix incorrect handling of shared nodes which only
worked for leaf nodes. This was due to the fact how the measure
was accumulated: it is possible that add() is called with an empty
measure.
Pull Request: https://projects.blender.org/blender/blender/pulls/134699
Sergey Sharybin
24fbd71a56