Using "Bake Navigation" in a GridMap with some MeshLibrary items without a NavigationRegion3D causes errors

[CubicMelon]

Tested versions

This issue is seen in both the latest Godot_v4.4-dev3 and Godot_v4.3-stable.

System information

Godot v4.4.dev3.mono - Windows 10.0.19045 - Multi-window, 2 monitors - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 3060 (NVIDIA; 32.0.15.6094) - AMD Ryzen 7 3700X 8-Core Processor (16 threads)

Issue description

When you have a GridMap in a scene that meets the following criteria:

• It has "Bake Navigation" on
• The MeshLibrary has one or more meshes that lack a NavigationRegion3D
• Meshes lacking that NavigationRegion3D are present in the painted grid items

Every time you switch from another tab back to the scene containing the GridMap, you get the following error repeated in the output window:
servers/rendering/renderer_rd/storage_rd/mesh_storage.cpp:807 - Parameter "mesh" is null.

This may be incorrect usage of a GridMap/MeshLibrary that I'm not aware of, but I would expect to be able to have only certain meshes have Navigation Regions since something like walls would not have any navigation at all. Regardless, an error like this should probably not occur I would imagine.

Steps to reproduce

Open the attached MRP. Switch from the mesh_library scene tab back to the main_scene tab and observe the error gets printed each time. If you uncheck "Bake Navigation" on the GridMap, the error does not appear.

Minimal reproduction project (MRP)

mesh-storage-error-mrp.zip