godot: Parse Error: [ext_resource] referenced non-loaded resource when loading a specific scene

Godot version

v4.0.alpha.mono.custom_build [67d401552]

System information

Ubuntu 22.04

Issue description

See the attached project for the scene in question. You get this error when trying to load it:

  scene/resources/resource_format_text.cpp:177 - res://SlidingDoor/SlidingDoor.tscn:8 - Parse Error: [ext_resource] referenced non-loaded resource at: res://SlidingDoor/SlidingDoor.tscn
  scene/resources/resource_format_text.cpp:610 - res://SlidingDoor/SlidingDoor.tscn:8 - Parse Error: [ext_resource] referenced non-loaded resource at: res://SlidingDoor/SlidingDoor.tscn
  Failed loading resource: res://SlidingDoor/SlidingDoor.tscn. Make sure resources have been imported by opening the project in the editor at least once.
  editor/editor_data.cpp:530 - Index p_idx = 1 is out of bounds (edited_scene.size() = 1).

Steps to reproduce

Simply open the attached project. The default scene fails to load.

When you re-import the blend file referenced in the SlidingDoor.tscn file the scene will load fine, until you save the scene which breaks it again. You can keep going round and round like that.

I believe it has something to do with this particular blend file, but I have yet to figure out what specifically is causing the issue. Also I had this issue on previous GD4 commits, but it went away and came back again, so I think a fix may have been reverted recently. If I find the commit where it broke, I’ll update this issue.

Minimal reproduction project

Bug.zip