Issue error if interpolate filter has no routes or tracks to operate on.

diff --git a/interpolate.cc b/interpolate.cc
index 4c39be8c237643448ca888667d6a99f71df20bd9..646c3747618230f2232689308ef22677967015d6 100644 (file)
--- a/interpolate.cc
+++ b/interpolate.cc
@@ -74,6 +74,11 @@ interpfilt_process(void)
     track_backup(&count, &backuproute);
     route_flush_all_tracks();
   }
+
+  if (count == 0) {
+    fatal(MYNAME ": Found no routes or tracks to operate on.\n");
+  }
+
   QUEUE_FOR_EACH(backuproute, elem, tmp) {
     route_head* rte_old = (route_head*)elem;