void Start()
    {
        ClassConstruction.Item Metal = null;
        System.Collections.Generic.Dictionary<Level, string> Metal_Name = null;
        System.Collections.Generic.Dictionary<Level, string> Metal_Description = null;

        Metal_Name.Add(Level.Level01, "Metall");
        Metal_Name.Add(Level.Level02, "Schwer Metall");
        Metal.object_name = Metal_Name;
        Metal_Description.Add(Level.Level01, "Herkömmliches Metall");
        Metal_Description.Add(Level.Level02, "Schwer Metall für höhere Stabilität");
        Metal.object_description = Metal_Description;
        UnityEngine.Debug.Log(UnityEngine.JsonUtility.ToJson(Metal));
    }


// Der Fehler:
NullReferenceException: Object reference not set to an instance of an object
ClassConstruction.Start () (at Assets/ShelfConstructor/Native_WORKSPACE/ClassConstruction.cs:18)