tenable.nessus: agents.list() exception: TypeError: object of type 'NoneType' has no len()

[dsobon]

Describe the bug

For tenable.nessus module, "api.agents.list()" fails if there are no agents linked to an instance of Nessus Manager.

To Reproduce

from tenable.nessus import Nessus
api = Nessus(url=...)
for item in api.agents.list(limit=1000, sort_by="name"):
    print(item)

Current behaviour

 File "./test.py", line 217, in agents_list
    for item in api.agents.list(limit=1000, sort_by="name"):
  File "/usr/local/lib/python3.8/dist-packages/restfly/iterator.py", line 114, in __next__
    return self.next()  # noqa: PLE1102
  File "/usr/local/lib/python3.8/dist-packages/restfly/iterator.py", line 146, in next
    if len(self.page) == 0:
TypeError: object of type 'NoneType' has no len()

Expected behavior

No exception triggered.