if there is no frame, there is no cng

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@7228 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/mod/applications/mod_esf/mod_esf.c

@@ -136,7 +136,7 @@ SWITCH_STANDARD_APP(bcast_function)
 
 	while(!ready) {
 		status = switch_core_session_read_frame(session, &read_frame, -1, 0);
-		if (switch_test_flag(read_frame, SFF_CNG)) {
+		if (read_frame && switch_test_flag(read_frame, SFF_CNG)) {
 			continue;
 		}