### 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_READ_THREAD_GUARD_V(0);
	return theme_owner->get_theme_default_base_scale();
}
Ref<Font> Window::get_theme_default_font() const {
	ERR_READ_THREAD_GUARD_V(Ref<Font>());
	return theme_owner->get_theme_default_font();
}
int Window::get_theme_default_font_size() const {
	ERR_READ_THREAD_GUARD_V(0);
	return theme_owner->get_theme_default_font_size();
}
void Window::begin_bulk_theme_override() {
	ERR_MAIN_THREAD_GUARD;
	bulk_theme_override = true;
}
void Window::end_bulk_theme_override() {
	ERR_MAIN_THREAD_GUARD;
	ERR_FAIL_COND(!bulk_theme_override);
	bulk_theme_override = false;
	_notify_theme_override_changed();
}
Rect2i Window::get_parent_rect() const {
	ERR_READ_THREAD_GUARD_V(Rect2i());
	ERR_FAIL_COND_V(!is_inside_tree(), Rect2i());
	if (is_embedded()) {