### Godot version

v4.0.beta.custom_build [eaf306e0b]

### System information

Windows 10

### Issue description

Selecting a `Window` node in the Editor's SceneTree results in the message
```
editor/editor_data.cpp:1058 - Parameter "p_node" is null.
```
and the Inspector shows empty content instead of the Window's properties.

I would expect, that clicking on a node in the SceneTree lets me edit the properties of the node.

Bisecting shows that this behavior got introduced in #71770

### Steps to reproduce

1. Create a Window node
2. Click on the Window node in the Editor's SceneTree

### Minimal reproduction project

N/A
include_own_types = p_enable;
}
ThemeTypeDialog::ThemeTypeDialog() {
	set_hide_on_ok(false);
	VBoxContainer *add_type_vb = memnew(VBoxContainer);
	add_child(add_type_vb);
	Label *add_type_filter_label = memnew(Label);
	add_type_filter_label->set_text(TTR("Filter the list of types or create a new custom type:"));
	add_type_vb->add_child(add_type_filter_label);
	add_type_filter = memnew(LineEdit);
	add_type_vb->add_child(add_type_filter);
	add_type_filter->connect("text_changed", callable_mp(this, &ThemeTypeDialog::_add_type_filter_cbk));
	add_type_filter->connect("text_submitted", callable_mp(this, &ThemeTypeDialog::_add_type_dialog_entered));
	Label *add_type_options_label = memnew(Label);
	add_type_options_label->set_text(TTR("Available Node-based types:"));
	add_type_vb->add_child(add_type_options_label);
	add_type_options = memnew(ItemList);
	add_type_options->set_v_size_flags(Control::SIZE_EXPAND_FILL);
	add_type_vb->add_child(add_type_options);
	add_type_options->connect("item_selected", callable_mp(this, &ThemeTypeDialog::_add_type_options_cbk));
	add_type_options->connect("item_activated", callable_mp(this, &ThemeTypeDialog::_add_type_dialog_activated));
	add_type_confirmation = memnew(ConfirmationDialog);
	add_type_confirmation->set_title(TTR("Type name is empty!"));
	add_type_confirmation->set_text(TTR("Are you sure you want to create an empty type?"));
	add_type_confirmation->connect("confirmed", callable_mp(this, &ThemeTypeDialog::_add_type_confirmed));
	add_child(add_type_confirmation);
}
VBoxContainer *ThemeTypeEditor::_create_item_list(Theme::DataType p_data_type) {