LoRa: Dont try to send until connected

lorawan.cpp

@@ -184,7 +184,7 @@ namespace lorawan {
   void preparePayloadIfTimeHasCome(const int16_t &co2, const float &temperature, const float &humidity) {
     static unsigned long last_sent_at = 0;
     unsigned long now = seconds();
-    if (now - last_sent_at > config::lorawan_sending_interval) {
+    if (connected && (now > last_sent_at + config::lorawan_sending_interval)) {
       last_sent_at = now;
       preparePayload(co2, temperature, humidity);
     }