### 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.
int center_split_offset = center_split->get_split_offset();
	p_config_file->set_value(EDITOR_NODE_CONFIG_SECTION, "center_split_offset", center_split_offset);
	int selected_bottom_panel_item_idx = -1;
	for (int i = 0; i < bottom_panel_items.size(); i++) {
		if (bottom_panel_items[i].button->is_pressed()) {
			selected_bottom_panel_item_idx = i;
			break;
		}
	}
	if (selected_bottom_panel_item_idx != -1) {
		p_config_file->set_value(EDITOR_NODE_CONFIG_SECTION, "selected_bottom_panel_item", selected_bottom_panel_item_idx);
	}
	
	int selected_default_debugger_tab_idx = EditorDebuggerNode::get_singleton()->get_default_debugger()->get_current_debugger_tab();
	p_config_file->set_value(EDITOR_NODE_CONFIG_SECTION, "selected_default_debugger_tab_idx", selected_default_debugger_tab_idx);
	
	int selected_main_editor_idx = -1;
	for (int i = 0; i < main_editor_buttons.size(); i++) {
		if (main_editor_buttons[i]->is_pressed()) {
			selected_main_editor_idx = i;
			break;
		}
	}
	if (selected_main_editor_idx != -1) {
		p_config_file->set_value(EDITOR_NODE_CONFIG_SECTION, "selected_main_editor_idx", selected_main_editor_idx);
	}
}
void EditorNode::_load_central_editor_layout_from_config(Ref<ConfigFile> p_config_file) {