routing: ensure we set the TotalFees value on routes properly

Before this commit, we wouldn’t properly set the TotalFees attribute.
As a result, our sorting algorithm at the end to select candidate
routes would simply maintain the time-lock order rather than also sort
by total fees. This commit fixes this issue and also allows the test
added in the prior commit to pass.

routing/pathfind.go

@@ -302,6 +302,8 @@ func newRoute(amtToSend lnwire.MilliSatoshi, sourceVertex Vertex,
 		}
 		edge.Node.PubKey.Curve = nil
 
+		route.TotalFees += nextHop.Fee
+
 		// As a sanity check, we ensure that the selected channel has
 		// enough capacity to forward the required amount which
 		// includes the fee dictated at each hop.

routing/router_test.go

@@ -186,7 +186,7 @@ func TestFindRoutesFeeSorting(t *testing.T) {
 			routes[0].TotalFees)
 	}
 	if routes[1].TotalFees == 0 {
-		t.Fatalf("total fees not set in second route: ",
+		t.Fatalf("total fees not set in second route: %v",
 			spew.Sdump(routes[0]))
 	}