Getting "Attempted to spawn an Actor outside of a service" error

[pipex]

Hi, I posted something related to this in spectrum but also adding it here.

In my company we are evaluating the use of xstate and I'm working on a proof of concept for controlling an embedded device state using xstates (with actors).

I'm getting the Attempted to spawn an Actor outside of a service error when spawning a child but not sure what I'm doing wrong.

I replicated the problem with two actors in a sandbox here.

https://codesandbox.io/s/admiring-paper-blktf?file=/src/index.ts

If anyone has any suggestions I'd love to hear them

[davidkpiano]

Working on a fix for this! #1290

It should be an innocuous warning, but it will be solved when that PR goes in.

[pipex]

Thanks @davidkpiano, I also just realised there is a bug in my example

For spawning a child I was doing

actions: assign({ ponger: spawn(ponger) })

But it should be

actions: assign({ ponger: () => spawn(ponger) })

Awesome work with the framework btw, I think is very powerful and an awesome way to bring model-based design into modern development.

[davidkpiano]

The (tentative) plan for V5 will be to have spawned entities be lazy by default, so that this would be possible:

actions: assign({ ponger: spawn(() => ponger) });

// This is also okay
actions: assign({ ponger: () => spawn(() => ponger) });

And this should never occur (will throw an error):

// none of these are lazy spawns
actions: assign({ ponger: spawn(ponger) }); // ❌
actions: assign({ ponger: () => spawn(ponger) }); // ❌

This is not implemented yet in V5, but will be.

[pipex]

Another question, somewhat related. I see that the spawn function is overloaded to return an Interpreter or an actor.

But when I do

actions: assign({ ponger: () => spawn(ponger) })

The typescript compiler usually complains with the warning Type 'Actor<PongContext, PongEvent>' is missing the following properties from type 'Interpreter<PongContext, any, PongEvent, any>'.

Can you think of any way to coerce the assignment to prevent this?

[davidkpiano]

In V5 these will always be ActorRef types (same as an actor, don't worry about the difference for now), but have you tried as Actor?

[pipex]

🤦🏻‍♂️ was trying something a lot more complicated, thanks again