Shadow meshes give error Can't use compression flag 'ARRAY_FLAG_COMPRESS_ATTRIBUTES' and null ARRAY_VERTEX

[lyuma]

Godot version

4.2.beta1 a574c02

System information

Godot v4.2.beta (a574c02) - Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce RTX 3090 (NVIDIA; 31.0.15.3713) - Intel(R) Core(TM) i9-9900K CPU @ 3.60GHz (16 Threads)

Issue description

Calling Mesh.surface_get_arrays() on a shadow mesh appears to print errors such as

  Can't use compression flag 'ARRAY_FLAG_COMPRESS_ATTRIBUTES' while using normals without tangent array.
  scene\resources\mesh.cpp:1795 - Condition "err != OK" is true.
  scene\resources\mesh.cpp:1936 - Index p_idx = 0 is out of bounds (surfaces.size() = 0).
  scene\resources\mesh.cpp:1916 - Index p_idx = 0 is out of bounds (surfaces.size() = 0).

and returns arrays with the ARRAY_VERTEX array being null.

My code does:

	func adjust_mesh_scale(mesh: ArrayMesh, is_shadow: bool = false):
		push_warning("Processing mesh " + str(mesh) + " is_shadow=" + str(is_shadow))
		for surf_idx in range(surf_count):
			var prim: int = mesh.surface_get_primitive_type(surf_idx)
			var fmt_compress_flags: int = mesh.surface_get_format(surf_idx)
			var arr: Array = mesh.surface_get_arrays(surf_idx)

			push_warning("Surface " + str(surf_idx) + " : Arrays len is " + str(len(arr)) + " (should be " + str(ArrayMesh.ARRAY_INDEX + 1) + ")")
			push_warning("Surface " + str(surf_idx) + " : ARRAY_VERTEX (" + str(ArrayMesh.ARRAY_VERTEX) + ") should be type " + str(typeof(PackedVector3Array())) + " : " + str(typeof(arr[0])))
			push_warning("Surface " + str(surf_idx) + " : len(arr[ARRAY_VERTEX]) is.....")
			push_warning(len(arr[0])) # Crashes on surface 1?????

		...

		if not is_shadow and mesh.shadow_mesh != mesh and mesh.shadow_mesh != null:
			adjust_mesh_scale(mesh.shadow_mesh, true)

Here is the output on this function when processing both the conventional mesh and the shadow mesh:

  core\variant\variant_utility.cpp:1033 - Processing mesh <ArrayMesh#-9223369631605918152> is_shadow=false
  core\variant\variant_utility.cpp:1033 - Surface 0 : Arrays len is 13 (should be 13)
  core\variant\variant_utility.cpp:1033 - Surface 0 : ARRAY_VERTEX (0) should be type 36 : 36
  core\variant\variant_utility.cpp:1033 - Surface 0 : len(arr[ARRAY_VERTEX]) is.....
  core\variant\variant_utility.cpp:1033 - 8280
  Can't use compression flag 'ARRAY_FLAG_COMPRESS_ATTRIBUTES' while using normals without tangent array.
  scene\resources\mesh.cpp:1795 - Condition "err != OK" is true.
  scene\resources\mesh.cpp:1936 - Index p_idx = 0 is out of bounds (surfaces.size() = 0).
  scene\resources\mesh.cpp:1916 - Index p_idx = 0 is out of bounds (surfaces.size() = 0).
  core\variant\variant_utility.cpp:1033 - Processing mesh <ArrayMesh#-9223369631589142756> is_shadow=true
  core\variant\variant_utility.cpp:1033 - Surface 0 : Arrays len is 13 (should be 13)
  core\variant\variant_utility.cpp:1033 - Surface 0 : ARRAY_VERTEX (0) should be type 36 : 0
  core\variant\variant_utility.cpp:1033 - Surface 0 : len(arr[ARRAY_VERTEX]) is.....
  res://test_post_import.gd:271 - Error calling GDScript utility function '<unknown function>': Value of type 'Nil' can't provide a length.

Steps to reproduce

1. Open the attached project.
2. Clear the console
3. Reimport Godot.glb

Minimal reproduction project

mesh_post_import.zip