### Godot version

v4.2.dev.custom_build [0c2144da9]

### System information

Debian Linux X11 Xfce

### Issue description

Prerequisite: Be in Single Window Mode in the Editor
The Filesystem Dock is unusable when it is floating, which is not expected.
It appears garbled in the top-left corner:
![image](https://github.com/godotengine/godot/assets/6299227/109f7922-97de-44c3-814a-ca7f970e0602)

The following errors are shown:
```
  editor/window_wrapper.cpp:220 - Condition "!is_window_available()" is true.
  editor/window_wrapper.cpp:202 - Condition "!get_window_enabled()" is true. Returning: Rect2i()
  editor/window_wrapper.cpp:207 - Condition "!get_window_enabled()" is true. Returning: -1
  editor/window_wrapper.cpp:207 - Condition "!get_window_enabled()" is true. Returning: -1
```

bisecting lead to #62378
possibly related to #44439

### Steps to reproduce

1. Start a project in the Editor
2. Switch to Single Window Mode in the Editor and reload (if necessary)
3. Make the Filesystem Dock floating

### Minimal reproduction project

Editor issue
ERR_FAIL_NULL(p_editing_owner);
	if (p_object && _is_class_editor_disabled_by_feature_profile(p_object->get_class())) {
		return;
	}
	Vector<EditorPlugin *> item_plugins;
	if (p_object) {
		item_plugins = editor_data.get_subeditors(p_object);
	}
	if (!item_plugins.is_empty()) {
		ObjectID owner_id = p_editing_owner->get_instance_id();
		List<EditorPlugin *> to_remove;
		for (EditorPlugin *plugin : active_plugins[owner_id]) {
			if (!item_plugins.has(plugin)) {
				
				to_remove.push_back(plugin);
				_plugin_over_edit(plugin, nullptr);
			}
		}
		for (EditorPlugin *plugin : to_remove) {
			active_plugins[owner_id].erase(plugin);