### 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
if (Object::cast_to<Theme>(p_node)) {
		return true;
	}
	Ref<Theme> edited_theme = theme_editor->get_edited_theme();
	if (edited_theme.is_null()) {
		return false;
	}
	
	
	
	bool belongs_to_theme = false;
	if (Object::cast_to<Font>(p_node)) {
		Ref<Font> font_item = Object::cast_to<Font>(p_node);
		List<StringName> types;
		List<StringName> names;
		edited_theme->get_font_type_list(&types);
		for (const StringName &E : types) {
			names.clear();
			edited_theme->get_font_list(E, &names);
			for (const StringName &F : names) {
				if (font_item == edited_theme->get_font(F, E)) {
					belongs_to_theme = true;
					break;
				}
			}
		}
	} else if (Object::cast_to<StyleBox>(p_node)) {
		Ref<StyleBox> stylebox_item = Object::cast_to<StyleBox>(p_node);
		List<StringName> types;
		List<StringName> names;