How a failure propagates in a graph — the spec's failureSemantics, restated here so this module
stays free of entity imports.
'block' (the default) means a failure is terminal for everything downstream. 'edges' means a
flow's failure handling IS its outgoing edges, so a failed step's drawn recovery path runs.
How a failure propagates in a graph — the spec's
failureSemantics, restated here so this module stays free of entity imports.'block'(the default) means a failure is terminal for everything downstream.'edges'means a flow's failure handling IS its outgoing edges, so a failed step's drawn recovery path runs.