`AttributeError` while handling `sqlite3.OperationalError`

[phargogh]

Just got a report with the following traceback:

Traceback (most recent call last):
  File "C:\DS_Beneficiaries\downstream-beneficiaries.py", line 278, in <module>
    main()
  File "C:\DS_Beneficiaries\downstream-beneficiaries.py", line 267, in main
    calculate_downstream_beneficiaries(
  File "C:\DS_Beneficiaries\downstream-beneficiaries.py", line 122, in calculate_downstream_beneficiaries
    graph = taskgraph.TaskGraph(
  File "C:\Users\ntrahan\AppData\Local\ESRI\conda\envs\NatCapPyGeo\lib\site-packages\taskgraph\Task.py", line 333, in _init_
    _create_taskgraph_table_schema(self._task_database_path)
  File "C:\Users\ntrahan\AppData\Local\ESRI\conda\envs\NatCapPyGeo\lib\site-packages\taskgraph\Task.py", line 223, in _create_taskgraph_table_schema
    _execute_sqlite(
  File "C:\Users\ntrahan\AppData\Local\ESRI\conda\envs\NatCapPyGeo\lib\site-packages\retrying.py", line 49, in wrapped_f
    return Retrying(*dargs, **dkw).call(f, *args, **kw)
  File "C:\Users\ntrahan\AppData\Local\ESRI\conda\envs\NatCapPyGeo\lib\site-packages\retrying.py", line 212, in call
    raise attempt.get()
  File "C:\Users\ntrahan\AppData\Local\ESRI\conda\envs\NatCapPyGeo\lib\site-packages\retrying.py", line 247, in get
    six.reraise(self.value[0], self.value[1], self.value[2])
  File "C:\Users\ntrahan\AppData\Local\ESRI\conda\envs\NatCapPyGeo\lib\site-packages\six.py", line 719, in reraise
    raise value
  File "C:\Users\ntrahan\AppData\Local\ESRI\conda\envs\NatCapPyGeo\lib\site-packages\retrying.py", line 200, in call
    attempt = Attempt(fn(*args, **kwargs), attempt_number, False)
  File "C:\Users\ntrahan\AppData\Local\ESRI\conda\envs\NatCapPyGeo\lib\site-packages\taskgraph\Task.py", line 1563, in _execute_sqlite
    connection = sqlite3.connect(database_path)
sqlite3.OperationalError: unable to open database file
ERROR:taskgraph.Task:ignoring an exception that occurred during _terminate
Traceback (most recent call last):
  File "C:\Users\ntrahan\AppData\Local\ESRI\conda\envs\NatCapPyGeo\lib\site-packages\taskgraph\Task.py", line 842, in _terminate
    if self._n_workers >= 0:
AttributeError: 'TaskGraph' object has no attribute '_n_workers'