TypeError: 'NoneType' object is not subscriptable when attempting to start two sharded clusters on the same ports

[ShaneHarvey]

We’re seeing test runs where mongo-orchestration sends this back to the client in an HTTP 500 response:

Traceback (most recent call last):
  File "/data/mci/09d9293805bba164c02aa32f53e57a72/src/github.com/10gen/mongosync/venv/lib/python3.10/site-packages/mongo_orchestration/apps/__init__.py", line 66, in wrap
    return f(*arg, **kwd)
  File "/data/mci/09d9293805bba164c02aa32f53e57a72/src/github.com/10gen/mongosync/venv/lib/python3.10/site-packages/mongo_orchestration/apps/sharded_clusters.py", line 147, in sh_create_by_id
    result = _sh_create(data)
  File "/data/mci/09d9293805bba164c02aa32f53e57a72/src/github.com/10gen/mongosync/venv/lib/python3.10/site-packages/mongo_orchestration/apps/sharded_clusters.py", line 44, in _sh_create
    cluster_id = ShardedClusters().create(params)
  File "/data/mci/09d9293805bba164c02aa32f53e57a72/src/github.com/10gen/mongosync/venv/lib/python3.10/site-packages/mongo_orchestration/sharded_clusters.py", line 533, in create
    cluster = ShardedCluster(params)
  File "/data/mci/09d9293805bba164c02aa32f53e57a72/src/github.com/10gen/mongosync/venv/lib/python3.10/site-packages/mongo_orchestration/sharded_clusters.py", line 103, in __init__
    f.result()
  File "/opt/mongodbtoolchain/revisions/69f4f0673ffcb290ce2307560a4883ecf2ad138c/stow/python3-v4.hzp/lib/python3.10/concurrent/futures/_base.py", line 446, in result
    return self.__get_result()
  File "/opt/mongodbtoolchain/revisions/69f4f0673ffcb290ce2307560a4883ecf2ad138c/stow/python3-v4.hzp/lib/python3.10/concurrent/futures/_base.py", line 391, in __get_result
    raise self._exception
  File "/opt/mongodbtoolchain/revisions/69f4f0673ffcb290ce2307560a4883ecf2ad138c/stow/python3-v4.hzp/lib/python3.10/concurrent/futures/thread.py", line 58, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/data/mci/09d9293805bba164c02aa32f53e57a72/src/github.com/10gen/mongosync/venv/lib/python3.10/site-packages/mongo_orchestration/sharded_clusters.py", line 96, in add_shard
    info = self.member_add(cfg.get('id', None), shard_params)
  File "/data/mci/09d9293805bba164c02aa32f53e57a72/src/github.com/10gen/mongosync/venv/lib/python3.10/site-packages/mongo_orchestration/sharded_clusters.py", line 400, in member_add
    result = self._add(cfgs, member_id)
  File "/data/mci/09d9293805bba164c02aa32f53e57a72/src/github.com/10gen/mongosync/venv/lib/python3.10/site-packages/mongo_orchestration/sharded_clusters.py", line 377, in _add
    return self.router_command("addShard", (shard_uri, {"name": name}), is_eval=False)
  File "/data/mci/09d9293805bba164c02aa32f53e57a72/src/github.com/10gen/mongosync/venv/lib/python3.10/site-packages/mongo_orchestration/sharded_clusters.py", line 366, in router_command
    result = getattr(self.connection().admin, mode)(command, name, **d)
  File "/data/mci/09d9293805bba164c02aa32f53e57a72/src/github.com/10gen/mongosync/venv/lib/python3.10/site-packages/mongo_orchestration/sharded_clusters.py", line 334, in connection
    return self.create_connection(self.router['hostname'])
TypeError: 'NoneType' object is not subscriptable

This happens when attempting to start two sharded clusters on the same ports, or more exactly, when starting a mongos on port X but something else is already running on port X, most likely another mongo server.