stop crash caused by missing conditional

diff --git a/libs/ardour/route.cc b/libs/ardour/route.cc
index 0b8a0b8ff379c8defea5b13e4db4514ad4643722..29709e3cbaafdf0eebf46ce8f930486433be6a7e 100644 (file)
--- a/libs/ardour/route.cc
+++ b/libs/ardour/route.cc
@@ -738,10 +738,12 @@ Route::passthru_silence (framepos_t start_frame, framepos_t end_frame, pframes_t
 void
 Route::set_listen (bool yn)
 {
-       if (yn) {
-               _monitor_send->activate ();
-       } else {
-               _monitor_send->deactivate ();
+       if (_monitor_send) {
+               if (yn) {
+                       _monitor_send->activate ();
+               } else {
+                       _monitor_send->deactivate ();
+               }
        }
 }