fix(sdk): cloud.Service hangs on long-running inflight functions (#4089)

Fixes #4086

## Checklist

- [x] Title matches [Winglang's style guide](https://www.winglang.io/contributing/start-here/pull_requests#how-are-pull-request-titles-formatted)
- [x] Description explains motivation and solution
- [x] Tests added (always)
- [ ] Docs updated (only required for features)
- [ ] Added `pr/e2e-full` label if this feature requires end-to-end testing

*By submitting this pull request, I confirm that my contribution is made under the terms of the [Wing Cloud Contribution License](https://github.com/winglang/wing/blob/main/CONTRIBUTION_LICENSE.md)*.

libs/wingsdk/src/target-sim/service.inflight.ts

@@ -55,7 +55,8 @@ export class Service implements IServiceClient, ISimulatorResourceInstance {
       sourceType: SERVICE_TYPE,
       timestamp: new Date().toISOString(),
     });
-    await fnClient.invoke("");
+    // eslint-disable-next-line @typescript-eslint/no-floating-promises
+    fnClient.invoke("");
     this.running = true;
   }
 

libs/wingsdk/test/target-sim/service.test.ts

@@ -9,6 +9,14 @@ async handle(message) {
   console.log("Service Started");
 }`;
 
+const INFLIGHT_ON_START_WITH_LOOP = `
+async handle(message) {
+  console.log("Service Started");
+  while (true) {
+    await new Promise((resolve) => setTimeout(resolve, 1000));
+  }
+}`;
+
 const INFLIGHT_ON_STOP = `
 async handle(message) {
   console.log("Service Stopped");
@@ -42,6 +50,29 @@ test("create a service with on start method", async () => {
   expect(app.snapshot()).toMatchSnapshot();
 });
 
+test(
+  "on start method does not block other resources from deploying",
+  async () => {
+    // GIVEN
+    const app = new SimApp();
+    const handler = Testing.makeHandler(
+      app,
+      "OnStartHandler",
+      INFLIGHT_ON_START_WITH_LOOP
+    );
+    cloud.Service._newService(app, "my_service", {
+      onStart: handler,
+    });
+
+    // WHEN
+    const s = await app.startSimulator();
+
+    // THEN
+    await s.stop();
+  },
+  { timeout: 10000 }
+);
+
 test("create a service with a on stop method", async () => {
   // Given
   const app = new SimApp();