fix some npe

src/main/java/ru/r2cloud/device/SdrServerDevice.java

@@ -63,6 +63,9 @@ public void reCalculateFrequencyBands(List<Transmitter> scheduledTransmitters) {
 
 		List<BandFrequency> bandwidths = new ArrayList<>();
 		for (Transmitter curTransmitter : scheduledTransmitters) {
+			if (curTransmitter.getBaudRates().isEmpty()) {
+				continue;
+			}
 			Integer maxBaudRate = Collections.max(curTransmitter.getBaudRates());
 			if (maxBaudRate == null) {
 				continue;
@@ -96,7 +99,9 @@ public void reCalculateFrequencyBands(List<Transmitter> scheduledTransmitters) {
 			}
 			currentBandTransmitters.add(cur.getTransmitter());
 		}
-		transmittersPerBand.put(currentBand, currentBandTransmitters);
+		if (currentBand != null) {
+			transmittersPerBand.put(currentBand, currentBandTransmitters);
+		}
 		LOG.info("[{}] active bands are:", id);
 		for (Entry<BandFrequency, List<Transmitter>> cur : transmittersPerBand.entrySet()) {
 			LOG.info("  {} - {}", cur.getKey().getLower(), cur.getKey().getUpper());

src/main/java/ru/r2cloud/model/Transmitter.java

@@ -2,6 +2,7 @@
 
 import java.util.ArrayList;
 import java.util.Base64;
+import java.util.Collections;
 import java.util.Date;
 import java.util.List;
 
@@ -91,19 +92,19 @@ public Transmitter(Transmitter copy) {
 			this.updated = new Date(copy.updated.getTime());
 		}
 	}
-	
+
 	public int getPriorityIndex() {
 		return priorityIndex;
 	}
-	
+
 	public void setPriorityIndex(int priorityIndex) {
 		this.priorityIndex = priorityIndex;
 	}
-	
+
 	public long getFrequencyBand() {
 		return frequencyBand;
 	}
-	
+
 	public void setFrequencyBand(long frequencyBand) {
 		this.frequencyBand = frequencyBand;
 	}
@@ -369,6 +370,8 @@ public static Transmitter fromJson(JsonObject asObject) {
 				bauds.add(baudRatesArray.get(i).asInt());
 			}
 			result.setBaudRates(bauds);
+		} else {
+			result.setBaudRates(Collections.emptyList());
 		}
 		JsonValue modulation = asObject.get("modulation");
 		if (modulation != null) {