Error when loading scene with custom AABB on a GeometryInstance3D

[pwajnkaim]

Tested versions

Reproducable in v4.2.stable.mono

System information

Godot v4.2.stable.mono - Windows 10.0.22621 - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 3070 (NVIDIA; 31.0.15.4617) - AMD Ryzen 5 5600X 6-Core Processor (12 Threads)

Issue description

When you edit the custom bounding box for the GeometryInstance3D in a MeshInstance3D, subsequently opening up the scene containing the node, it throws a cpp error.
servers/rendering/renderer_scene_cull.cpp:1019 - Condition "!is_geometry_instance(instance->base_type)" is true.
This also causes the custom AABB to be ignored and revert to default behaviour.

Steps to reproduce

Create a MeshInstance3D.
Edit 'Custom AABB' in the GeometryInstance3D section.
Save the scene and re-open it.

Minimal reproduction project (MRP)

AABB_test.zip

[MajorMcDoom]

Would like to mention that this is still happening in 4.3.

[Calinou]

This is also printed whenever Custom AABB is printed if no mesh is currently assigned. This likely occurs because Custom AABB is being set before the mesh is actually assigned.

Ideally, we should make it possible to properly assign a custom AABB even if no mesh has been assigned (it can be handy for run-time loading and avoids some pitfalls). See also #89538.