fix: ChatGPT_API_with_finish_reason returns inconsistent type on error

[luojiyin1987]

Problem

The ChatGPT_API_with_finish_reason function returns different types depending on success/failure:

• Success: returns (content: str, finish_reason: str) tuple
• Error (max retries): returns "Error" string

This causes unpacking errors at call sites expecting a tuple.

Location

pageindex/utils.py:57 - error return in retry loop

Expected Behavior

Return ("", "error") tuple to maintain consistent return type.

Fix

Change error return from:

return "Error"

To:

return "", "error"