clarify empty design message. See Isse #204

icetime/icetime.cc

diff --git a/icetime/icetime.cc b/icetime/icetime.cc
index a5a27a0..e7c0cd7 100644
--- a/icetime/icetime.cc
+++ b/icetime/icetime.cc
@@ -925,7 +925,7 @@
 		if (n.empty()) {
 			n = global_max_path_net;
 			if (n.empty()) {
-				fprintf(stderr, "No path found!\n");
+				fprintf(stderr, "This design is empty. It contains no paths!\n");
 				exit(1);
 			}
 			if (frpt) {