Nest.js - Error on EventSource when using Server side event

Question

I am using Nest.js and I want to send Observable stream to the client

The Nest controller is:

  const stopTimer$ = timer(3000);

  @Sse('getGeneratedTitle')
  async test() {
    return interval(1000).pipe(
      map(_ => ({ data: { hello: 'world' } })),
      takeUntil(stopTimer$)
    );
  }

And this is the method on ServiceApi on the client side:

getStreamCompletion =  () => {
      const eventSource = new EventSource('api/getGeneratedTitle');

      eventSource.onmessage = (event) => {
        console.log(event.data);
      };

      eventSource.onerror = (error) => {
        console.error("Oops!" + error);
      };
  };

The problem is, I'm always getting an error on the client when the stream ended:

ServiceApi.ts:21 {"hello":"world"}
ServiceApi.ts:21 {"hello":"world"}
ServiceApi.ts:25(onerror) Oops! Event {isTrusted: true, type: 'error', target: EventSource, currentTarget: EventSource, eventPhase: 2, …}

Any thoughts what is the issue and how to solve it? Thanks!