### Godot version

4.2 eca6f0e

### System information

Windows 10 x64

### Issue description


https://github.com/godotengine/godot/assets/2223172/a2796263-4e2e-4b14-a080-b3ad034cc141



### Steps to reproduce

1. Add SubViewport
2. Add Sprite2D
3. Set spirte's texture to ViewportTexture
4. Create new scene
5. Instance the new scene inside the scene with viewport
6. Make sure both scenes are opened
7. Go to instance scene and save it
8. Go to viewport scene

You will see error spam. Reloading the scene fixes it.

### Minimal reproduction project

[vip.zip](https://github.com/godotengine/godot/files/12292386/vip.zip)

bool is_size_2d_override_stretch_enabled() const override;
	void set_update_mode(UpdateMode p_mode);
	UpdateMode get_update_mode() const;
	void set_clear_mode(ClearMode p_mode);
	ClearMode get_clear_mode() const;
	virtual Transform2D get_screen_transform_internal(bool p_absolute_position = false) const override;
	virtual Transform2D get_popup_base_transform() const override;
	virtual bool is_directly_attached_to_screen() const override;
	virtual bool is_attached_in_viewport() const override;
	virtual bool is_sub_viewport() const override { return true; };
	void _validate_property(PropertyInfo &p_property) const;
	SubViewport();
	~SubViewport();
};
VARIANT_ENUM_CAST(Viewport::Scaling3DMode);
VARIANT_ENUM_CAST(SubViewport::UpdateMode);
VARIANT_ENUM_CAST(Viewport::PositionalShadowAtlasQuadrantSubdiv);
VARIANT_ENUM_CAST(Viewport::MSAA);
VARIANT_ENUM_CAST(Viewport::ScreenSpaceAA);
VARIANT_ENUM_CAST(Viewport::DebugDraw);
VARIANT_ENUM_CAST(Viewport::SDFScale);
VARIANT_ENUM_CAST(Viewport::SDFOversize);
VARIANT_ENUM_CAST(Viewport::VRSMode);
VARIANT_ENUM_CAST(SubViewport::ClearMode);
VARIANT_ENUM_CAST(Viewport::RenderInfo);
VARIANT_ENUM_CAST(Viewport::RenderInfoType);
VARIANT_ENUM_CAST(Viewport::DefaultCanvasItemTextureFilter);
VARIANT_ENUM_CAST(Viewport::DefaultCanvasItemTextureRepeat);
#endif