When self.factor is set to a type not available from okta, program crashes

[EStallings]

Describe the bug
When self.factor is set to a type not available from okta (which happens if you change your okta mfa settings) program crashes with this error:

  File "/usr/local/bin/okta-awscli", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.9/site-packages/click/core.py", line 1130, in __call__
    return self.main(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/click/core.py", line 1055, in main
    rv = self.invoke(ctx)
  File "/usr/local/lib/python3.9/site-packages/click/core.py", line 1404, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/usr/local/lib/python3.9/site-packages/click/core.py", line 760, in invoke
    return __callback(*args, **kwargs)
  File "/usr/local/lib/python3.9/site-packages/oktaawscli/okta_awscli.py", line 141, in main
    get_credentials(
  File "/usr/local/lib/python3.9/site-packages/oktaawscli/okta_awscli.py", line 36, in get_credentials
    _, assertion = okta.get_assertion()
  File "/usr/local/lib/python3.9/site-packages/oktaawscli/okta_auth.py", line 156, in get_assertion
    self.session_token = self.primary_auth()
  File "/usr/local/lib/python3.9/site-packages/oktaawscli/okta_auth.py", line 59, in primary_auth
    session_token = mfa_base.verify_mfa(factors_list)
  File "/usr/local/lib/python3.9/site-packages/oktaawscli/okta_auth_mfa_base.py", line 71, in verify_mfa
    supported_factors[factor_choice]['provider'])
UnboundLocalError: local variable 'factor_choice' referenced before assignment
    Error: Command failed: okta-awscli --okta-profile global --profile global --verbose

To Reproduce
Steps to reproduce the behavior:

1. Edit your okta file or your okta mfa settings
2. Attempt to login via okta-awscli

Expected behavior
At a minimum a more informative error message would help clarify what's going on

Environment (please complete the following information):

• OS: MacOS
• Version of okta-awscli you're running: 0.5.4