mypy Unsupported operand types for + ("str" and "timedelta") [operator]

maillepaille.log

maillepaille.py:10: error: Incompatible types in assignment (expression has type "datetime", variable has type "str")  [assignment]
maillepaille.py:15: error: Incompatible types in assignment (expression has type "date", variable has type "str")  [assignment]
maillepaille.py:17: error: Incompatible types in assignment (expression has type "datetime", variable has type "str")  [assignment]
maillepaille.py:19: error: Unsupported operand types for + ("str" and "timedelta")  [operator]

maillepaille.py

from datetime import date, datetime, timedelta, timezone

import pytz

yesterday = ""
now = datetime.now(tz=pytz.timezone("Europe/London"))
today = date.today()

if yesterday:
    yesterday = datetime.strptime(yesterday, "%Y-%m-%d").replace(tzinfo=timezone.utc)

    start_of_day = yesterday

else:
    yesterday = today - timedelta(days=1, seconds=-1)

    start_of_day = datetime(now.year, now.month, now.day)

end_of_day = start_of_day + timedelta(days=1, seconds=-1)

Nomme la variable différement quand c'est une chaîne et une date alors, ça aidera mypy à suivre.