{
  "error": {
    "code": "internal server error",
    "message": "Traceback (most recent call last):\n  File \"./ores/wsgi/routes/v3/scores.py\", line 28, in process_score_request\n    score_response = scoring_system.score(score_request)\n  File \"./ores/scoring_systems/scoring_system.py\", line 42, in score\n    response = self._score(request)\n  File \"./ores/scoring_systems/celery_queue.py\", line 192, in _score\n    return super()._score(*args, **kwargs)\n  File \"./ores/scoring_systems/scoring_system.py\", line 61, in _score\n    self._build_model_info(request, response)\n  File \"./ores/scoring_systems/scoring_system.py\", line 122, in _build_model_info\n    context.format_model_info(model_name, request.model_info))\n  File \"./ores/scoring_context.py\", line 39, in format_model_info\n    return model_info.format(paths, formatting=\"json\")\n  File \"/srv/deployment/ores/venv/lib/python3.4/site-packages/revscoring/scoring/model_info.py\", line 106, in format\n    return self.format_json(path_tree, **kwargs)\n  File \"/srv/deployment/ores/venv/lib/python3.4/site-packages/revscoring/scoring/model_info.py\", line 130, in format_json\n    d[key] = key_val.format_json(sub_tree, **kwargs)\n  File \"/srv/deployment/ores/venv/lib/python3.4/site-packages/revscoring/scoring/statistics/classification/classification.py\", line 164, in format_json\n    doc[key] = self[key].format_json(sub_tree, **kwargs)\n  File \"/srv/deployment/ores/venv/lib/python3.4/site-packages/revscoring/scoring/model_info.py\", line 130, in format_json\n    d[key] = key_val.format_json(sub_tree, **kwargs)\n  File \"/srv/deployment/ores/venv/lib/python3.4/site-packages/revscoring/scoring/statistics/classification/scaled_threshold_statistics.py\", line 135, in format_json\n    threshold, pstats = opt.get_optimal(self)\nTypeError: 'NoneType' object is not iterable\n"
  }
}