test(e2e): add test for "ID-TAKEN" twice in a row

See https://github.com/peers/peerjs/issues/180#issuecomment-1689993774
Follow-up to 1005bdf012

e2e/peer/id-taken.html

@@ -28,7 +28,14 @@
 				.once("open", (id) =>
 					new Peer(id).once(
 						"error",
-						(error) => void (messages.textContent = JSON.stringify(error)),
+						(error) => {
+							messages.textContent = JSON.stringify(error);
+							// At the time of writng the second one succeeds for some reason.
+							new Peer(id).once(
+								"error",
+								(error) => void (errorMessage.textContent = JSON.stringify(error)),
+							);
+						},
 					),
 				);
 		</script>

e2e/peer/peer.spec.ts

@@ -5,6 +5,7 @@ describe("Peer", () => {
 	it("should emit an error, when the ID is already taken", async () => {
 		await P.open("id-taken");
 		await P.waitForMessage('{"type":"unavailable-id"}');
+		await P.waitForMessage('{"type":"unavailable-id"}');
 		expect(await P.errorMessage.getText()).toBe("");
 	});
 	it("should emit an error, when the server is unavailable", async () => {