AP_Mount: get_angle_target_to_location checks for valid location

libraries/AP_Mount/AP_Mount_Backend.cpp

@@ -252,6 +252,11 @@ bool AP_Mount_Backend::get_angle_target_to_location(const Location &loc, MountTa
         return false;
     }
 
+    // exit immediate if location is invalid
+    if (!loc.initialised()) {
+        return false;
+    }
+
     const float GPS_vector_x = Location::diff_longitude(loc.lng, current_loc.lng)*cosf(ToRad((current_loc.lat + loc.lat) * 0.00000005f)) * 0.01113195f;
     const float GPS_vector_y = (loc.lat - current_loc.lat) * 0.01113195f;
     int32_t target_alt_cm = 0;