KeyError when executing master branch qdstat -l (links) against 1.9.0 router on Python 3

Run the following test in a Python 3 environment -

1. Start version 1.9.0 of the router
2. Run a qdstat -l command against the 1.9.0 router
3. You will see an error --> KeyError: deliveriesStuck

You should be able to run a newer qdstat command against the currently released version of the router (1.9.0)

Note: This works when running the router on Python 2.7 but fails when running the router on Python 3.8