### Godot version

4.1.beta (7b1387ff2)

### System information

Mageia 9, Linux

### Issue description

When opening an empty project in latest `master`, I get these errors:
```
ERROR: Index p_idx = -1 is out of bounds (edited_scene.size() = 1).
   at: get_scene_path (editor/scu/../editor_data.cpp:880)
ERROR: Index p_idx = -1 is out of bounds (edited_scene.size() = 1).
   at: check_and_update_scene (editor/scu/../editor_data.cpp:683)
ERROR: Index p_idx = -1 is out of bounds (edited_scene.size() = 1).
   at: set_edited_scene (editor/scu/../editor_data.cpp:745)
```

Possibly related to recent changes to restore past sessions, but there's nothing to restore in this case?

### Steps to reproduce

- Create a new project, edit it
- Quit to project manager
- Re-open the newly created project -> errors

### Minimal reproduction project

Empty project.
help_menu->set_item_icon(help_menu->get_item_index(HELP_QA), gui_base->get_theme_icon(SNAME("ExternalLink"), SNAME("EditorIcons")));
			help_menu->set_item_icon(help_menu->get_item_index(HELP_REPORT_A_BUG), gui_base->get_theme_icon(SNAME("ExternalLink"), SNAME("EditorIcons")));
			help_menu->set_item_icon(help_menu->get_item_index(HELP_COPY_SYSTEM_INFO), gui_base->get_theme_icon(SNAME("ActionCopy"), SNAME("EditorIcons")));
			help_menu->set_item_icon(help_menu->get_item_index(HELP_SUGGEST_A_FEATURE), gui_base->get_theme_icon(SNAME("ExternalLink"), SNAME("EditorIcons")));
			help_menu->set_item_icon(help_menu->get_item_index(HELP_SEND_DOCS_FEEDBACK), gui_base->get_theme_icon(SNAME("ExternalLink"), SNAME("EditorIcons")));
			help_menu->set_item_icon(help_menu->get_item_index(HELP_COMMUNITY), gui_base->get_theme_icon(SNAME("ExternalLink"), SNAME("EditorIcons")));
			help_menu->set_item_icon(help_menu->get_item_index(HELP_ABOUT), gui_base->get_theme_icon(SNAME("Godot"), SNAME("EditorIcons")));
			help_menu->set_item_icon(help_menu->get_item_index(HELP_SUPPORT_GODOT_DEVELOPMENT), gui_base->get_theme_icon(SNAME("Heart"), SNAME("EditorIcons")));
			for (int i = 0; i < main_editor_buttons.size(); i++) {
				main_editor_buttons.write[i]->add_theme_font_override("font", gui_base->get_theme_font(SNAME("main_button_font"), SNAME("EditorFonts")));
				main_editor_buttons.write[i]->add_theme_font_size_override("font_size", gui_base->get_theme_font_size(SNAME("main_button_font_size"), SNAME("EditorFonts")));
			}
			HashSet<String> updated_textfile_extensions;
			bool extensions_match = true;
			const Vector<String> textfile_ext = ((String)(EDITOR_GET("docks/filesystem/textfile_extensions"))).split(",", false);
			for (const String &E : textfile_ext) {
				updated_textfile_extensions.insert(E);
				if (extensions_match && !textfile_extensions.has(E)) {
					extensions_match = false;
				}
			}
			if (!extensions_match || updated_textfile_extensions.size() < textfile_extensions.size()) {
				textfile_extensions = updated_textfile_extensions;
				EditorFileSystem::get_singleton()->scan();
			}
			_update_update_spinner();
		} break;
	}
}
void EditorNode::_update_update_spinner() {