### 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.
load_scene(p_resource->get_path().get_slice("::", 0));
	InspectorDock::get_singleton()->call_deferred("edit_resource", p_resource);
}
bool EditorNode::is_resource_read_only(Ref<Resource> p_resource, bool p_foreign_resources_are_writable) {
	ERR_FAIL_COND_V(p_resource.is_null(), false);
	String path = p_resource->get_path();
	if (!path.is_resource_file()) {
		
		int srpos = path.find("::");
		if (srpos != -1) {
			String base = path.substr(0, srpos);
			
			if (ResourceLoader::get_resource_type(base) == "PackedScene") {
				if (!get_tree()->get_edited_scene_root() || get_tree()->get_edited_scene_root()->get_scene_file_path() != base) {
					
					
					if (!p_foreign_resources_are_writable || FileAccess::exists(base + ".import")) {
						return true;
					}
				}
			} else {
				
				if (FileAccess::exists(base + ".import")) {