The `rna_Scene_ray_cast()` function tried to find the current depsgraph. To
this end, it required the scene, the view layer, and bmain. Scene has a cache
of per-view-layer depsgraphs, to speed up switching between view layers. This
cache does not contain render depsgraphs, and evaluated view layers also don't
have a depsgraph here.
When a suitable depsgraph cannot be found, a new depsgraph is created. However,
this depsgraph is not evaluated, and has an unexpanded scene pointer with a
`NULL` `view_layer`. Using this then crashes Blender. Also, there was no way
for the code to get the render depsgraph.
The solution is to pass the depsgraph to the `ray_cast()` function, instead of
the view layer. This avoids the depsgraph lookup, and also works correctly when
rendering.
Some add-ons also need updating, which I'll do in the `addons`
repository soon.
Reviewed By: Sergey
Differential Revision: https://developer.blender.org/D8475
e03d53874d