[feature request] finally in machine

[rozbo]

Description:

Currently, xstate support catch error by subscribe, but if something store in context, or created by callback actor, once error raised, these resource can't be cleanup
image this.

describe('Callback actor with error threw', () => {
  let counter = 1;
  let isOver = false; // a flag to detect clean or not.
  const machine = setup({
    actors: {
      test: fromCallback(({ sendBack }) => {
        const aa = setInterval(() => {
          counter++;
          sendBack({ type: 'haha' + counter });
        }, 100);
        return () => {
          clearInterval(aa);
          isOver = true; // mark we cleand it.
        };
      }),
    },
  }).createMachine({
    invoke: {
      src: 'test',
    },
    initial: 'idle',
    states: {
      idle: {
        on: {
          haha3: {
            actions: () => {
              throw new Error('haha');
            },
          },
        },
      },
    },
  });
  it('should works when throw error', async () => {
    const actor = createActor(machine);
    actor.start();
    // setTimeout(() => {
    //   actor.stop();
    // }, 300);
    try {
      await toPromise(actor);
    } catch (e) {
      actor.stop(); // this not work cause the machine status is error.
      // console.log(actor.getSnapshot());
      expect(e.message).toMatch('haha'); // ✅  we not catch the Error we threw.
    }
    expect(counter).toBeGreaterThan(2); // ✅
    expect(isOver).toBeTruthy(); // 🔴 this will failed , the cleanup function can't reach
  });
});

So, can we provide a way to clean there resource in machine? like Promise's finally , then we can clean some resource whatever whenever whereever errors threw. so that we can coding happly without care about resource cleanup.

ref: https://discord.com/channels/795785288994652170/1203727111312121987

[davidkpiano]

@Andarist Perhaps the right thing to do is to stop all running actors if an error occurs?