### 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.
main_vbox->add_child(title_bar);
	left_l_hsplit = memnew(HSplitContainer);
	main_vbox->add_child(left_l_hsplit);
	left_l_hsplit->set_v_size_flags(Control::SIZE_EXPAND_FILL);
	left_l_vsplit = memnew(VSplitContainer);
	left_l_hsplit->add_child(left_l_vsplit);
	dock_slot[DOCK_SLOT_LEFT_UL] = memnew(TabContainer);
	left_l_vsplit->add_child(dock_slot[DOCK_SLOT_LEFT_UL]);
	dock_slot[DOCK_SLOT_LEFT_BL] = memnew(TabContainer);
	left_l_vsplit->add_child(dock_slot[DOCK_SLOT_LEFT_BL]);
	left_r_hsplit = memnew(HSplitContainer);
	left_l_hsplit->add_child(left_r_hsplit);
	left_r_vsplit = memnew(VSplitContainer);
	left_r_hsplit->add_child(left_r_vsplit);
	dock_slot[DOCK_SLOT_LEFT_UR] = memnew(TabContainer);
	left_r_vsplit->add_child(dock_slot[DOCK_SLOT_LEFT_UR]);
	dock_slot[DOCK_SLOT_LEFT_BR] = memnew(TabContainer);
	left_r_vsplit->add_child(dock_slot[DOCK_SLOT_LEFT_BR]);
	main_hsplit = memnew(HSplitContainer);
	left_r_hsplit->add_child(main_hsplit);
	VBoxContainer *center_vb = memnew(VBoxContainer);
	main_hsplit->add_child(center_vb);
	center_vb->set_h_size_flags(Control::SIZE_EXPAND_FILL);
	center_split = memnew(VSplitContainer);
	center_split->set_v_size_flags(Control::SIZE_EXPAND_FILL);
	center_split->set_collapsed(false);
	center_vb->add_child(center_split);
	right_hsplit = memnew(HSplitContainer);
	main_hsplit->add_child(right_hsplit);
	right_l_vsplit = memnew(VSplitContainer);