Circular dependencies of scenes (by preload) cause a script can not be loaded

[jinyangcruise]

Godot version

v4.0.beta10.official [d0398f6]

System information

Vulkan API 1.3.205 - Using Vulkan Device #0: NVIDIA - NVIDIA GeForce RTX 3060 Ti

Issue description

My project contains two scenes "cell.tscn"（attached with a script "cell.gd") and "swap_pad.tscn" (attached with a script "swap_pad.gd"). Everytime I open this project, the "cell.tscn" always lose its script "cell.gd" with an error log :

ERROR: res://src/swapPad/cell.tscn:9 - Parse Error: [ext_resource] referenced non-loaded resource at: res://src/swapPad/cell.gd
   at: _parse_ext_resource (scene/resources/resource_format_text.cpp:178)

I need to re-attach this script to the scene to fix it temporarily but next time this problem happen again.
I finally figured out this problem happens if two scripts have circular dependencies. I don't know if this problem is or not a bug of Godot. If not, why can I fix it temporarily by re-attach the script to the scene.

Content of "cell.gd":

extends CenterContainer

var _swapPad : SwapPad = null

Content of "swap_pad.gd"

extends Control
class_name SwapPad

func _ready():
	var cellClass := preload("res://src/swapPad/cell.tscn")

Steps to reproduce

0.download minimal reproduction project below

1. open project
2. open cell.tscn（src/swapPad）in godot and you will find this scene have no script
3. attach cell.gd to cell.tscn
4. save and close project
5. open project again
6. open cell.tscn（src/swapPad）in godot and you will find this scene still have no script

Minimal reproduction project

test1.zip

[Chaosus]

cc @adamscott

[adamscott]

I confirm this issue. This does not seem to be a regression. I'm investigating.

[dalexeev]

See also:

• Parse Error: [ext_resource] referenced non-loaded resource when loading a specific scene #64330
• "Bad address index" error is printed when there is a cyclic reference in a script #74253
• Nonexistent resource error when trying to use change_scene_to_packed() to change the scene to a PackedScene via an exported variable when the target scene also has a reference to the first scene #77090
• preload cause ' cyclic resource inclusion' error #77436
• Scenes unable to be opened upon cylic preload() in script #78128
• Scene is invalid/corrupt according to the Godot editor, but works normally ingame #79545

[adamscott]

For more info on this issue and why it's currently difficult to fix it, see the comments of my closed PR #71004.

[keir]

I put up #80854 to help make the user experience of this engine limitation easier to debug/deal with.

[Muhammad-Fiqri]

I got the same problem.
The scene that get added to the scene with the error script lose its script and unable to be functional