Remove obsolete function

Remove obsolete function and typing annotations

(cherry picked from commit 0469541)

gspread/exceptions.py

@@ -6,7 +6,7 @@
 
 """
 
-from typing import Any, Dict, Mapping, Optional, Union
+from typing import Any, Mapping
 
 from requests import Response
 
@@ -45,15 +45,6 @@ def __init__(self, response: Response):
  self.error: Mapping[str, Any] = response.json()["error"]
  self.code: int = self.error["code"]
 
- def _extract_error(
- self, response: Response
- ) -> Optional[Dict[str, Union[int, str]]]:
- try:
- errors = response.json()
- return dict(errors["error"])
- except (AttributeError, KeyError, ValueError):
- return None
-
  def __str__(self) -> str:
  return "{}: [{}]: {}".format(
  self.__class__.__name__, self.code, self.error["message"]