[stdlib] Allow FileHandler.stream to be None

FileHandler sets self.stream = None in two CPython code paths:
delay=True in __init__ and after close(). Override the inherited
StreamHandler.stream type to reflect this.

Author: rgant

stdlib/@tests/test_cases/check_logging.py

@@ -1,11 +1,14 @@
 from __future__ import annotations
 
+import io
 import logging
 import logging.handlers
 import multiprocessing
 import queue
 from typing import Any
 
+from typing_extensions import assert_type
+
 # This pattern comes from the logging docs, and should therefore pass a type checker
 # See https://docs.python.org/3/library/logging.html#logrecord-objects
 
@@ -28,3 +31,7 @@ def record_factory(*args: Any, **kwargs: Any) -> logging.LogRecord:
 logging.handlers.QueueListener(queue.Queue())
 logging.handlers.QueueListener(queue.SimpleQueue())
 logging.handlers.QueueListener(multiprocessing.Queue())
+
+# FileHandler.stream can be None when delay=True or after close()
+fh = logging.FileHandler("test.log", delay=True)
+assert_type(fh.stream, io.TextIOWrapper | None)

stdlib/logging/__init__.pyi

@@ -616,6 +616,7 @@ class FileHandler(StreamHandler[TextIOWrapper]):
     encoding: str | None  # undocumented
     delay: bool  # undocumented
     errors: str | None  # undocumented
+    stream: TextIOWrapper | None  # type: ignore[assignment]  # None when delay=True or after close()
     def __init__(
         self, filename: StrPath, mode: str = "a", encoding: str | None = None, delay: bool = False, errors: str | None = None
     ) -> None: ...