Lifecycle node error processing improvements

[mjforan]

Feature request

Feature description

The lifecycle/managed node state machine will move to the ErrorProcessing state and trigger the on_error callback when there is a transition error or an uncaught exception. However, there is no way to retrieve the error information within that callback. Instead the error handler has to infer what happened by digging through the state of the node.

Implementation considerations

Maybe pass a reference to the exception as an argument to on_error or store it as a member of the LifecycleNode class.