Lightmap UV generation on rigged FBX files causes the mesh to disappear

[QbieShay]

Godot version

v4.2.dev.custom_build [3ed4497]

System information

Fedora, RX 590

Issue description

When attempting to use the lightmap unwrap on a rigged fbx (doesn't repro with glb), there's an error in the console and the mesh disappears.

I created this mesh in blender as a reproduction case, but this issue was observed yesterday on minionsart's stream (https://www.twitch.tv/videos/1924312339, problems starting at 2h32 min roughly). She kindly sent me the model and I've managed to make a reproduction case that behave the same way (see MRP below)

Steps to reproduce

Download MRP

There's an fbx (test2.fbx). It's a cube rigged to a metarig.

Double click the FBX, you'll see a cube mesh

Hit reimport

Open the test_2.tscn, observe the cube is missing

with errors in the console

  scene/resources/importer_mesh.cpp:337 - Index bone_idx = 545021568 is out of bounds (static_cast<int>(bone_transform_vector.size()) = 159).
 servers/rendering_server.cpp:599 - Condition "array.size() != (int32_t)(p_vertex_array_len * bone_count)" is true. Returning: ERR_INVALID_PARAMETER
 Invalid array format for surface.
 scene/resources/mesh.cpp:1771 - Condition "err != OK" is true.
 scene/resources/mesh.cpp:1892 - Index p_idx = -1 is out of bounds (surfaces.size() = 0).
 scene/resources/mesh.cpp:1912 - Index p_idx = -1 is out of bounds (surfaces.size() = 0).
 Attempt to disconnect a nonexistent connection from 'test2:<Node3D#1917988171855>'. Signal: 'replacing_by', callable: 'EditorNode::set_edited_scene

Minimal reproduction project

minions-test.zip