def wsgi_errors_stream() -> t.TextIO:
    """Find the most appropriate error stream for the application. If a request
    is active, log to ``wsgi.errors``, otherwise use ``sys.stderr``.

    If you configure your own :class:`logging.StreamHandler`, you may want to
    use this for the stream. If you are using file or dict configuration and
    can't import this directly, you can refer to it as
    ``ext://flask.logging.wsgi_errors_stream``.
    """
    if request:
        return request.environ["wsgi.errors"]  # type: ignore[no-any-return]

    return sys.stderr
Find the most appropriate error stream for the application. If a request
    is active, log to ``wsgi.errors``, otherwise use ``sys.stderr``.

    If you configure your own :class:`logging.StreamHandler`, you may want to
    use this for the stream. If you are using file or dict configuration and
    can't import this directly, you can refer to it as
    ``ext://flask.logging.wsgi_errors_stream``.
    
src/flask/logging.py