Traceback when doing connected query for role that does not exist

[sethsec]

Describe the bug
Traceback when doing connected query for role that does not exist

To Reproduce
Steps to reproduce the behavior, please include information on suspected users/roles that are the source of the issue when possible:
❯ pmapper --profile test-terraform query 'preset connected role/does-not-exist *'

Traceback:

Traceback (most recent call last):
  File "/opt/homebrew/bin/pmapper", line 8, in <module>
    sys.exit(main())
  File "/opt/homebrew/lib/python3.9/site-packages/principalmapper/__main__.py", line 149, in main
    return query_cli.process_arguments(parsed_args)
  File "/opt/homebrew/lib/python3.9/site-packages/principalmapper/querying/query_cli.py", line 123, in process_arguments
    query_actions.query_response(
  File "/opt/homebrew/lib/python3.9/site-packages/principalmapper/querying/query_actions.py", line 137, in query_response
    handle_preset(graph, query, skip_admins)
  File "/opt/homebrew/lib/python3.9/site-packages/principalmapper/querying/query_actions.py", line 193, in handle_preset
    connected.handle_preset_query(graph, tokens, skip_admins)
  File "/opt/homebrew/lib/python3.9/site-packages/principalmapper/querying/presets/connected.py", line 43, in handle_preset_query
    print_connected_results(graph, source_nodes, dest_nodes, skip_admins)
  File "/opt/homebrew/lib/python3.9/site-packages/principalmapper/querying/presets/connected.py", line 53, in print_connected_results
    connection_result, path = is_connected(graph, snode, dnode)
  File "/opt/homebrew/lib/python3.9/site-packages/principalmapper/querying/presets/connected.py", line 82, in is_connected
    edge_lists = get_search_list(graph, source_node)
  File "/opt/homebrew/lib/python3.9/site-packages/principalmapper/querying/query_utils.py", line 40, in get_search_list
    if node.is_admin:
AttributeError: 'NoneType' object has no attribute 'is_admin'

Expected behavior
Should handle error gracefully. maybe telling me the user does not exist?

Version: principalmapper: stable 1.1.5 (bottled) (brew)