### 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
edit_items_add_font->set_disabled(true);
	edit_items_toolbar->add_child(edit_items_add_font);
	edit_items_add_font->connect("pressed", callable_mp(this, &ThemeItemEditorDialog::_open_add_theme_item_dialog).bind(Theme::DATA_TYPE_FONT));
	edit_items_add_font_size = memnew(Button);
	edit_items_add_font_size->set_tooltip_text(TTR("Add Font Size Item"));
	edit_items_add_font_size->set_flat(true);
	edit_items_add_font_size->set_disabled(true);
	edit_items_toolbar->add_child(edit_items_add_font_size);
	edit_items_add_font_size->connect("pressed", callable_mp(this, &ThemeItemEditorDialog::_open_add_theme_item_dialog).bind(Theme::DATA_TYPE_FONT_SIZE));
	edit_items_add_icon = memnew(Button);
	edit_items_add_icon->set_tooltip_text(TTR("Add Icon Item"));
	edit_items_add_icon->set_flat(true);
	edit_items_add_icon->set_disabled(true);
	edit_items_toolbar->add_child(edit_items_add_icon);
	edit_items_add_icon->connect("pressed", callable_mp(this, &ThemeItemEditorDialog::_open_add_theme_item_dialog).bind(Theme::DATA_TYPE_ICON));
	edit_items_add_stylebox = memnew(Button);
	edit_items_add_stylebox->set_tooltip_text(TTR("Add StyleBox Item"));
	edit_items_add_stylebox->set_flat(true);
	edit_items_add_stylebox->set_disabled(true);
	edit_items_toolbar->add_child(edit_items_add_stylebox);
	edit_items_add_stylebox->connect("pressed", callable_mp(this, &ThemeItemEditorDialog::_open_add_theme_item_dialog).bind(Theme::DATA_TYPE_STYLEBOX));
	edit_items_toolbar->add_child(memnew(VSeparator));
	Label *edit_items_toolbar_remove_label = memnew(Label);
	edit_items_toolbar_remove_label->set_text(TTR("Remove Items:"));
	edit_items_toolbar->add_child(edit_items_toolbar_remove_label);
	edit_items_remove_class = memnew(Button);
	edit_items_remove_class->set_tooltip_text(TTR("Remove Class Items"));
	edit_items_remove_class->set_flat(true);
	edit_items_remove_class->set_disabled(true);
	edit_items_toolbar->add_child(edit_items_remove_class);