Missed events in the startup of the React app

[cardil]

A loss of events can be observed in React component. After refresh of web browser, only the last event is being displayed:

When calling the endpoint from CLI all events are streamed:

$ http :8080/events
HTTP/1.1 200 OK
Cache-Control: no-cache
Connection: keep-alive
Content-Type: text/event-stream; charset=utf-8
Date: Thu, 13 Apr 2023 15:48:25 GMT
X-Powered-By: Express
X-SSE-Content-Type: application/cloudevents+json
transfer-encoding: chunked

data:{
    "data": {
        "a": {
            "b": "first"
        }
    },
    "datacontenttype": "application/json",
    "id": "41e1e914-bb01-41cb-83eb-5340d480c600",
    "source": "kn-event/v1.7.0",
    "specversion": "1.0",
    "time": "2023-04-13T15:45:13.216Z",
    "type": "dev.knative.cli.plugin.event.generic"
}

data:{
    "data": {
        "a": {
            "b": "second"
        }
    },
    "datacontenttype": "application/json",
    "id": "c34c0cd7-aa84-41e5-be30-cb07bea0a234",
    "source": "kn-event/v1.7.0",
    "specversion": "1.0",
    "time": "2023-04-13T15:45:19.460Z",
    "type": "dev.knative.cli.plugin.event.generic"
}

data:{
    "data": {
        "a": {
            "b": "third"
        }
    },
    "datacontenttype": "application/json",
    "id": "56141d84-01b7-46c5-bed2-13ae4761dc57",
    "source": "kn-event/v1.7.0",
    "specversion": "1.0",
    "time": "2023-04-13T15:48:21.141Z",
    "type": "dev.knative.cli.plugin.event.generic"
}
^C

I suspect this might be some kind of race in the following lines:

showcase/frontend/src/events/sse.ts

Lines 35 to 39 in a01a18c

	const sse = new EventSource(`${baseAddress}/events`, { withCredentials: true })
	sse.onmessage = (e: MessageEvent) => {
	const ce = new CloudEvent(JSON.parse(e.data))
	this.listeners.forEach((l) => l(ce))
	}

To reproduce:

1. Deploy an app
2. Send a few events, so you know their order (for example id==first, id==second, id=third)
3. Open/refresh the web page

Actual result

1. You will see just the last event being rendered

Expected result

1. You should see all the events collected, rendered properly

/kind bug