message: Check for closed session
  Fixes
diff: @@ -1468,7 +1468,8 @@ class BaseSession(SessionInterface):
  # NOTE(mrry): It is possible that `self._session.__del__()` could be
  # called before this destructor, in which case `self._session._session`
  # will be `None`.
  - if self._handle is not None and self._session._session is not None:
  + if (self._handle is not None and self._session._session is not None and
  + not self._session._closed):
  tf_session.TF_SessionReleaseCallable(
  self._session._session, self._handle)
  # pylint: enable=protected-access
  