Fixed segfault if system was not found Autopilot

src/az_drone_controller.cpp

@@ -78,7 +78,7 @@ bool AzDroneController::stateAutopilot(void)
 
     if (systems.size() == 0) {
         std::cerr << "No system found." << std::endl;
-        return 1;
+        return false;
     }
 
     std::optional<std::shared_ptr<System>> autopilot = mMavsdk.first_autopilot(AZ_GET_AUTOPILOT_TIMEOUT);