message: Removes potential noisy error message from gradient tape.
diff: @@ -767,7 +767,10 @@ class GradientTape(object):
  def __del__(self):
  if self._created_eagerly:
  + try:
  context.context().end_step()
  + except AttributeError:
  + pass
  def watch(self, tensor):
  """Ensures that `tensor` is being traced by this tape.
  