TypeError: 'NoneType' object is not iterable

[AshutoshUpadhya]

Describe the bug
While running the extract_tables example,, I am getting the error:

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/wand/cdefs/wandtypes.py", line 33, in __del__
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 954, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 887, in _find_spec
TypeError: 'NoneType' object is not iterable
Exception ignored in: <bound method c_magick_char_p.__del__ of c_magick_char_p(13662016)>
Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/wand/cdefs/wandtypes.py", line 33, in __del__
  File "<frozen importlib._bootstrap>", line 969, in _find_and_load
  File "<frozen importlib._bootstrap>", line 954, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 887, in _find_spec
TypeError: 'NoneType' object is not iterable

I checked online but the solutions are not working here
Can someone pls suggest any solution. Thanks

To Reproduce
Steps to reproduce the behavior:
Execute following lines :

 sudo extract_tables --train-pdf paleo/ml/train.pdf.list.paleo.not.scanned --gt-train paleo/ml/gt.train --test-pdf paleo/ml/test.pdf.list.paleo.not.scanned --gt-test paleo/ml/gt.test --datapath paleo/documents/ --model-path model.pkl

If necessary, attach example data which can be used to replicate the issue.

Expected behavior
The code should not fail.

Error Logs/Screenshots
If applicable, add error logs or screenshots to help explain your problem.

Environment (please complete the following information):

• OS: Ubuntu 16.04
• pdftotree Version: The latest master branch as of today(not sure of exact now)

[AshutoshUpadhya]

@lukehsiao : I tried all approaches I can search on stackoverflow, nbut its not working. Mostly they say abount python closing before environment close. I tried doing that but not successful. Can you pls see

[lukehsiao]

What python version are you using? Can you install pdftotree withing a virtual environment, rather than as sudo on your machine?

[HiromuHota]

From the original error messages and the report date, I can see:

1. Python 3.5
2. Wand 0.5.0 - 0.5.7 (wand/cdefs/wandtypes.py was added at 0.5.0 and 0.5.8 was released on December 5th, 2019).

Other than that, I cannot find anything else.
Closing for now but feel free to reopen when this issue still persists.