Problem creating templated instances derived from NetworkBehaviour

[infinityplusb]

Description

Creating a templated instance derived from NetworkBehaviour doesn't appear to compile. I'm following along with this youtube, which links to this git repo

Reproduce Steps

1. Create a templated class derived from NetworkBehaviour like

using UnityEngine;
using Unity.Netcode;

public class Singleton<T> : NetworkBehaviour
        where T : Component
{
    private static T _instance;
    public static T Instance
    {
        get
        {
            if (_instance == null)
            {
                var objs = FindObjectsOfType(typeof(T)) as T[];
                if (objs.Length > 0)
                    _instance = objs[0];
                if (objs.Length > 1)
                {
                    Debug.LogError("There is more than one " + typeof(T).Name + " in the scene.");
                }
                if (_instance == null)
                {
                    GameObject obj = new GameObject();
                    obj.name = string.Format("_{0}", typeof(T).Name);
                    _instance = obj.AddComponent<T>();
                }
            }
            return _instance;
        }
    }
}

2. Create a class from Singleton like so

using Unity.Netcode;
public class PlayerManager : Singleton<PlayerManager>
{
    NetworkVariable<int> playersInGame = new NetworkVariable<int>();

    public int PlayersInGame
    {
        get
        {
            return playersInGame.Value;
        }
    }
}

Actual Outcome

Sadness

(0,0): error  - System.NullReferenceException: Object reference not set to an instance of an object.||   at Unity.Netcode.Editor.CodeGen.INetworkSerializableILPP.Process(ICompiledAssembly compiledAssembly) in blah\Library\PackageCache\[email protected]\Editor\CodeGen\INetworkSerializableILPP.cs:line 116   at Unity.Netcode.Editor.CodeGen.INetworkSerializableILPP.Process(ICompiledAssembly compiledAssembly) in blah\Library\PackageCache\[email protected]\Editor\CodeGen\INetworkSerializableILPP.cs:line 116

Expected Outcome

Joy Being able to create a class, deriving from a templated networkbehaviour. Presumably this worked in previous iterations of Netcode as it's working in the tutorial video (created circa 5months ago)

Screenshots

If applicable, add screenshots to help explain your problem.

Environment

• OS: Windows 11
• Unity Version: 2021.3.2f1
• Netcode Version: 1.0.0-pre.8
• Netcode Commit: [e.g. https://github.com/Unity-Technologies/com.unity.netcode.gameobjects/commit/38a1510e155e32f9f4f31d218c704e0129c221ca]

Additional Context

The above linked (presumably previously working) repo looks to use "com.unity.netcode.gameobjects": "1.0.0-pre.3",

[infinityplusb]

This issue doesn't appear using "com.unity.netcode.gameobjects": "1.0.0-pre.7" but is using "com.unity.netcode.gameobjects": "1.0.0-pre.8" and "com.unity.netcode.gameobjects": "1.0.0-pre.9"