Bug YGNodeNewWithConfig is not allowed to be called from field initializer - Unity freeze on Play

I encountered an annoying bug when using UI Toolkit (1.0.0-preview.14).
Providing this sample code:

Code (CSharp):

1. using UnityEngine;
2. using UnityEngine.UIElements;
3.  
4. public class TestScript : MonoBehaviour
5. {
6.     VisualElement test = new VisualElement();
7. }
8.  

When scripts are compiled, you will get this error in your console:

YGNodeNewWithConfig is not allowed to be called from a MonoBehaviour constructor (or instance field initializer), call it in Awake or Start instead

I think there are two main issues here.

1) The first is that unity gives you this error only once. It can be cleared and you will not see it again until you open the scene with the script used inside. Plus this error does not block you from entering the play mode. When you try to enter play mode, Unity will just get stuck, frozen forever. When you force quit unity and reopen your project, you will get Failed to import window layout bug, but that is a whole different problem

2) This is more of a personal opinion, but it seems like a very bad design decision to forbid using constructor in field construction. Creating a new instance of class should be possible all the time. If not, constructors should be private and creating instances will be done through the factory.

When this turns into compile error...

Code (CSharp):

1. class Foo
2. {
3.    VisualElement test = VisualElement.Create();
4. }

.. its ok.

When this turns into compile error...

Code (CSharp):

1. class Foo
2. {
3.    VisualElement test = new VisualElement();
4. }

.. its NOT OK


The most important thing is the 1) I mentioned, this error should really prevent you from entering play mode.

 

I'm seeing this too. Has this not been addressed?

Specifically, this error will not only freeze the editor, but it will corrupt your entire project and require a near re-import to bring the editor back to a usable state. It's quite the harsh error state to get into with barely any notice for the user (I'm lucky I caught the error in the statusbar).