Guards allow us to conditionally take a transition when we react to an event.
cond property is a function that returns a boolean and recieves current event and context. This property is added to our transition object. Transition taken if cond returns true.
We can supply an array of transitions and take the first one that returns true from its cond function.
Rename our const to transitions and use toArray():
const transitions = toArray(stateConfig.on[eventObject.type])
Add a for ..of loop that returns early if a transition happens.