[core] Add spawned promise error test (#5010)

* Add spawned promise error test

* Oops

* Oops again

packages/core/test/actor.test.ts

@@ -1727,4 +1727,30 @@ describe('actors', () => {
 
     expect(spy).toHaveBeenCalledTimes(1);
   });
+
+  it('catches errors from spawned promise actors', () => {
+    expect.assertions(1);
+    const machine = createMachine({
+      on: {
+        event: {
+          actions: assign(({ spawn }) => {
+            spawn(
+              fromPromise(async () => {
+                throw new Error('uh oh');
+              })
+            );
+          })
+        }
+      }
+    });
+
+    const actor = createActor(machine);
+    actor.subscribe({
+      error: (err) => {
+        expect((err as Error).message).toBe('uh oh');
+      }
+    });
+    actor.start();
+    actor.send({ type: 'event' });
+  });
 });