test: fix nil dereference

fixes tests TestLoopOutFailOffchain,
TestLoopOutPaymentParameters

loopout_test.go

@@ -140,6 +140,18 @@ func testLoopOutPaymentParameters(t *testing.T) {
 	// this to prevent a blocked channel in the mock.
 	ctx.AssertRegisterConf(false, defaultConfirmations)
 
+	// Drive both payments to a terminal state so the async payment
+	// goroutines complete and don't hit a nil status path.
+	for _, p := range payments {
+		select {
+		case p.Updates <- lndclient.PaymentStatus{
+			State: lnrpc.Payment_SUCCEEDED,
+		}:
+		case <-time.After(test.Timeout):
+			t.Fatalf("could not send payment update")
+		}
+	}
+
 	// Cancel the swap. There is nothing else we need to assert. The payment
 	// parameters don't play a role in the remainder of the swap process.
 	cancel()

test/context.go

@@ -151,7 +151,7 @@ func (ctx *Context) AssertPaid(
 		return done
 	}
 
-	// Assert that client pays swap invoice.
+	// Assert that the client pays swap invoice.
 	for {
 		var swapPayment RouterPaymentChannelMessage
 		select {
@@ -171,7 +171,12 @@ func (ctx *Context) AssertPaid(
 
 		done := func(result error) {
 			if result != nil {
-				swapPayment.Errors <- result
+				// Send a terminal FAILED status so the client
+				// always receives a non-nil PaymentStatus and
+				// won't dereference nil.
+				swapPayment.Updates <- lndclient.PaymentStatus{
+					State: lnrpc.Payment_FAILED,
+				}
 				return
 			}
 			swapPayment.Updates <- lndclient.PaymentStatus{