Unified/D.R.Y. handling of errors from any of a state's invoked actors?

[James-E-A]

On every state which uses an invoked actor, I have a transition like this:

	error: { // asynchronous error in one of our invoked actors
		actions: "console_error",
		target: ".error",
	},

and then, in addition, on every invoked actor, I have a transition like this:

	onError: { // synchronous error in this invoked actor
		actions: "console_error",
		target: ".error",
	},

So if I have 2 states, each of which invokes 3 actors, then I have to use a total of eight transitions just to say "these 2 states should do such-and-such if there's an error".

That's a lot of boilerplate which creates a huge array of transitions that doesn't look very good in the Stately Editor autolayout, to boot.

Is there any way to have something like an "error:*" transition on a state which has invoked actors, to just have unified handling of onError for every invoked actor?

[DahanItamar]

In XState v5, invoked actor failures are delivered as xstate.error.actor.<actorId> events. You can catch them with a prefix wildcard:

on: {
  'xstate.error.actor.*': {
    actions: 'console_error',
    target: '.error',
  },
  error: {
    actions: 'console_error',
    target: '.error',
  },
},

Place this on block on a common parent if the states share an error destination. Here, .error means the error child of the state node containing this handler. If each state has its own .error child, put the block on each of those states instead; you still avoid an onError declaration for every individual invocation.

The plain error handler is only needed for actors that explicitly send your application event, e.g. sendBack({ type: 'error', error }). It is separate from XState's invoked-actor failure event.

Also, invoke.onError handles rejected promises as well as startup failures; it is not limited to synchronous errors. Remove local invoke.onError transitions when you want the common handler to handle those failures, because the more specific local transition takes precedence.

Tested with XState 5.33.2, including rejected promises, startup throws and local onError precedence. The relevant v5 error-event dispatch is here.