Unity 2022.3.4f1 NullReferenceException: Object reference not set to an instance of an object

[mdmm-git]

public static class GUIHelper { private static readonly GUIStyle _closeButtonStyle = GUI.skin.FindStyle("ToolbarSeachCancelButton");

    [PublicAPI] public static bool CloseButton(Rect buttonRect)
    {
        return GUI.Button(buttonRect, GUIContent.none, _closeButtonStyle);
        //NullReferenceException: Object reference not set to an instance of an object
    }

}