Godot: Can't run scene with `.res` or `.tres` extension

[RockyMadio]

Godot version:
3.2 ( from 3.1)

OS/device including version:
Windows 10

Issue description:
Play scene - buttons do not work as intended (F5 and F6, and Ctrl+Shift+F5)
Our project runs flawlessly in 3.1. However by clicking any of those, the latest 3.2 will always play the default scene (in the config) .

Removed the path in default scene setting, F6 and Ctrl+Shift+F5 will launch the default Godot project manager (list of launchable projects). F5 will ask for scene.

Changing the default scene with another scene will temporarily fix the issue. But it will repeat again as you want to F6 one another scene.
Steps to reproduce:
I am not sure how to reproduce this. A new project will not show this issue. But our project has already reached a big scale. There must be some conflicts in one of the conflig files. Please help :(

You would reproduce the bug like this : Create 2 scenes, A and B, make A default scene, close A, and F6 with B. if the game runs with A, it is the bug.

[KoBeWi]

What happens if you replace project.godot with an empty one?
It cold be some autoload node changing the scene.

[RockyMadio]

I tried, and it still shows the same issue. The empty project just lets me reset the default scene. As I repeated all steps mentioned above, It still does not change.

[RockyMadio]

This issue occures when you have level scenes as .res, changing them to .tscn will solve the problem. Most of my assets/instances are saved as .res, they still run properly.

[akien-mga]

Why close it? It seems you found a workaround/explanation but the bug is still present, no?

[RockyMadio]

Why close it? It seems you found a workaround/explanation but the bug is still present, no?

i thought it was a mistake on my end -.- So do you think it is a bug?

[KoBeWi]

Ok, I managed to confirm the issue. The problem is that you can't run scenes with .res extension (unless it's a main scene).

.res do appear as one of the extensions when saving scene

so either the bug should be fixed or the extension removed from the list.

[akien-mga]

While .res and .scn are exactly the same thing, I think it's likely fine to remove .res from the allowed extensions to reduce confusion. .tres is already missing even though it's also equivalent to .tscn.

On the other hand the engine itself should still be able to run scenes using .tres or .res if users do happen to force using these extensions for some reason. But if it works already with the main scene, I guess it's just the Play Scene code which adds this restriction.

[Calinou]

This is likely a regression from #33149. I guess we should allow using .res and .tres to run scenes as well.