UnityServer does not close in editor

[LukeStampfli]

To fix it, it should be enough to add:

#if UNITY_EDITOR
            EditorApplication.playModeStateChanged += (state) =>
            {
                if (state == PlayModeStateChange.ExitingPlayMode)
                {
                    Close();
                }
            };
#endif

In the OnEnable of the UnityServer. Make sure to also put the using UnityEditor in #if UNITY_Editor