### Godot version

4.1.dev (dc625bcbfc5b587ba8867481ee7a1f6a567c25d0)

### System information

Mageia 9, Linux

### Issue description

When importing a project in current `master`, the following error is raised for each asset that gets imported:
```
Attempting to parent and popup a dialog that already has a parent.
```

It seems to be raised once per asset, caused by the progress dialog.

CC @bruvzg

### Steps to reproduce

- Import a new project in Godot that contains importable assets, e.g. https://github.com/RPicster/godot4-demo-desert-light

### Minimal reproduction project

See above.
ERR_MAIN_THREAD_GUARD;
	ERR_FAIL_COND(!is_inside_tree());
	ERR_FAIL_COND_MSG(window_id == DisplayServer::MAIN_WINDOW_ID, "Can't popup the main window.");
	if (!is_embedded()) {
		Window *window = get_parent_visible_window();
		if (!window) {
			popup(p_parent_rect);
		} else {
			popup(Rect2i(window->get_position() + p_parent_rect.position, p_parent_rect.size));
		}
	} else {
		popup(p_parent_rect);
	}
}
void Window::popup_centered_clamped(const Size2i &p_size, float p_fallback_ratio) {