### 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.
if (p_editor->has_main_screen()) {
		
		
		for (int i = singleton->main_editor_buttons.size() - 1; i >= 0; i--) {
			if (p_editor->get_name() == singleton->main_editor_buttons[i]->get_text()) {
				if (singleton->main_editor_buttons[i]->is_pressed()) {
					singleton->editor_select(EDITOR_SCRIPT);
				}
				memdelete(singleton->main_editor_buttons[i]);
				singleton->main_editor_buttons.remove_at(i);
				break;
			} else {
				singleton->main_editor_buttons[i]->disconnect("pressed", callable_mp(singleton, &EditorNode::editor_select));
				singleton->main_editor_buttons[i]->connect("pressed", callable_mp(singleton, &EditorNode::editor_select).bind(i - 1));
			}
		}
		singleton->editor_table.erase(p_editor);
	}
	p_editor->make_visible(false);
	p_editor->clear();
	if (p_config_changed) {
		p_editor->disable_plugin();