### 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.
bottom_panel_updating = true;
		for (int i = 0; i < bottom_panel_items.size(); i++) {
			bottom_panel_items[i].button->set_pressed(i == p_idx);
			bottom_panel_items[i].control->set_visible(i == p_idx);
		}
		if (EditorDebuggerNode::get_singleton() == bottom_panel_items[p_idx].control) {
			
			bottom_panel->add_theme_style_override("panel", gui_base->get_theme_stylebox(SNAME("BottomPanelDebuggerOverride"), SNAME("EditorStyles")));
		} else {
			bottom_panel->add_theme_style_override("panel", gui_base->get_theme_stylebox(SNAME("BottomPanel"), SNAME("EditorStyles")));
		}
		center_split->set_dragger_visibility(SplitContainer::DRAGGER_VISIBLE);
		center_split->set_collapsed(false);
		if (bottom_panel_raise->is_pressed()) {
			top_split->hide();
		}
		bottom_panel_raise->show();
	} else {
		bottom_panel->add_theme_style_override("panel", gui_base->get_theme_stylebox(SNAME("BottomPanel"), SNAME("EditorStyles")));
		bottom_panel_items[p_idx].button->set_pressed(false);
		bottom_panel_items[p_idx].control->set_visible(false);
		center_split->set_dragger_visibility(SplitContainer::DRAGGER_HIDDEN);
		center_split->set_collapsed(true);
		bottom_panel_raise->hide();
		if (bottom_panel_raise->is_pressed()) {
			top_split->show();
		}
	}
}
void EditorNode::set_docks_visible(bool p_show) {