Using history states causes crash

[nobrayner]

See test_history_state in tests/test_machine.py for a failing example.

Line 175 uses singular transition property off of a StateNode which doesn't exist.
Similarly, Line 66 also tries to use a singular transition property

[nobrayner]

I noticed that SCION SCXML uses s.transitions[0] in this case. This strikes me as odd, as my interpretation of how this worked was different 😅

https://gitlab.com/scion-scxml/scion/-/blob/main/projects/libraries/core-base/lib/scion-core-base.js#L762