修复国标级联播放拉流代理空指针异常

src/main/java/com/genersoft/iot/vmp/streamProxy/service/impl/StreamProxyPlayServiceImpl.java

@@ -97,7 +97,7 @@ public class StreamProxyPlayServiceImpl implements IStreamProxyPlayService {
             streamProxy.setEnableMp4(record);
         }
         StreamInfo streamInfo = startProxy(streamProxy);
-        if (streamInfo != null) {
+        if (streamInfo != null && callback != null) {
             callback.run(ErrorCode.SUCCESS.getCode(), ErrorCode.SUCCESS.getMsg(), streamInfo);
         }
         return streamInfo;