修复启动偶现报错

src/main/java/com/genersoft/iot/vmp/gb28181/session/AudioBroadcastManager.java

@@ -87,7 +87,9 @@ public class AudioBroadcastManager {
     public List<AudioBroadcastCatch> get(String deviceId) {
         List<AudioBroadcastCatch> audioBroadcastCatchList= new ArrayList<>();
         if (SipUtils.isFrontEnd(deviceId)) {
-            audioBroadcastCatchList.add(data.get(deviceId));
+            if (data.get(deviceId) != null) {
+                audioBroadcastCatchList.add(data.get(deviceId));
+            }
         }else {
             for (String key : data.keySet()) {
                 if (key.startsWith(deviceId)) {