protect against null deref

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@7264 d0543943-73ff-0310-b7d9-9358b9ac24b2

src/mod/applications/mod_esf/mod_esf.c

@@ -140,7 +140,7 @@ SWITCH_STANDARD_APP(bcast_function)
 			continue;
 		}
 
-		if (!SWITCH_READ_ACCEPTABLE(status)) {
+		if (!SWITCH_READ_ACCEPTABLE(status) || !read_frame) {
 			goto fail;
 		}