itest: add delay after SubscribeSendEvents in sendAsset helper

The AssertSendEvents check in this function occasionally fails,
reporting that the first received event is
SendStateVirtualCommitmentSelect instead of the expected
SendStateStartHandleAddrParcel.

This likely occurs because the SubscribeSendEvents RPC returns before
the stream is fully initialized with the ChainPorter. As a result, the
SendAsset call may emit the first event before the stream listener is
ready to receive it.

Author: ffranr

itest/addrs_test.go

@@ -1013,6 +1013,15 @@ func sendAsset(t *harnessTest, sender *tapdHarness,
 		options.sendAssetRequest.SkipProofCourierPingCheck = true
 	}
 
+	// The SubscribeSendEvents call returns immediately, but the server may
+	// still be setting up its event stream. If we emit an event too soon,
+	// it may be lost. We wait briefly to allow the server time to complete
+	// setup.
+	//
+	// TODO(ffranr): Remove this once the server supports buffering or
+	//  replaying early events for new subscribers.
+	time.Sleep(time.Second)
+
 	// Kick off the send asset request.
 	resp, err := sender.SendAsset(ctxt, &options.sendAssetRequest)
 	if options.errText != "" {