This partially fixes T73593.
The `add_relation(driver_key, property_entry_key, ...);` call can fail
in the following situation:
- A collection is linked, and instanced into the scene by an Empty.
- The collection contains an object with a driver on its `hide_render` or
`hide_viewport` property.
As the object doesn't exist as a real object in the scene, it's added with
`base_index=-1` to the depsgraph (see `DepsgraphNodeBuilder::build_collection()`).
As a result the node for syncing the restrictflags back to the base
isn't present in the depsgraph, and the `add_relation()` call failed.
This commit fixes the warning, simply by not attempting to add the
offending relation.
Sybren A. Stüvel
94e180bd80