描述bug

在使用chatExcel时出现错误，

Traceback (most recent call last):
  File "/home/magic/workspace/github/eosphoros-ai/DB-GPT/pilot/scene/base_chat.py", line 173, in nostream_call
    self.prompt_template.output_parser.parse_prompt_response(
  File "/home/magic/workspace/github/eosphoros-ai/DB-GPT/pilot/scene/chat_data/chat_excel/excel_analyze/out_parser.py", line 38, in parse_prompt_response
    return ExcelAnalyzeResponse(sql, thoughts, display)
UnboundLocalError: local variable 'sql' referenced before assignment

桌面(请填写以下信息):

• 操作系统：Ubuntu 20.02
• 浏览器：Chroma
• LLM模型：vicuna-13b-v1.5