Cannot understand why I get this error

Exception ignored in: <bound method FaceNet.__del__ of <bob.project.swan.biometric_recognition.base_facenet_face_eyes.FaceNetExtractor object at 0x7fd9637b6358>>
Traceback (most recent call last):
  File "/remote/idiap.svm/user.active/amohammadi/git/deep/src/bob.ip.tensorflow_extractor/bob/ip/tensorflow_extractor/FaceNet.py", line 139, in __del__
TypeError: 'NoneType' object is not callable

@tiago.pereira do you have any idea?