Handle newlines with multiple consecutive data fields on eventStream (#…

…343)

Server-Sent Events handle multi-line data with multiple consecutive data
fields.

* [Spec](https://web.dev/articles/eventsource-basics#multi-line_data)
* [Client-side
code](https://github.com/mpetazzoni/sse.js/blob/febdf09b9d3434b9ab59207519f6ff9dd30d97b0/lib/sse.js#L234)

This PR adds support for newlines as expected.

src/server/event-stream.ts

@@ -34,7 +34,10 @@ export function eventStream(
 
 			function send({ event = "message", data }: SendFunctionArgs) {
 				controller.enqueue(encoder.encode(`event: ${event}\n`));
-				controller.enqueue(encoder.encode(`data: ${data}\n\n`));
+				data.split("\n").forEach((line) => {
+					controller.enqueue(encoder.encode(`data: ${line}\n`));
+				})
+				controller.enqueue(encoder.encode("\n"));
 			}
 
 			let cleanup = init(send, close);