修复定时删除过期录像文件时，收藏文件被删除的问题

src/main/java/com/genersoft/iot/vmp/service/impl/StreamProxyServiceImpl.java

@@ -133,6 +133,9 @@ public class StreamProxyServiceImpl implements IStreamProxyService {
             JSONArray dataArray = jsonObject.getJSONArray("data");
             JSONObject mediaServerConfig = dataArray.getJSONObject(0);
             String ffmpegCmd = mediaServerConfig.getString(param.getFfmpegCmdKey());
+            if (ffmpegCmd == null) {
+                throw new ControllerException(ErrorCode.ERROR100.getCode(), "ffmpeg拉流代理无法获取ffmpeg cmd");
+            }
             String schema = getSchemaFromFFmpegCmd(ffmpegCmd);
             if (schema == null) {
                 throw new ControllerException(ErrorCode.ERROR100.getCode(), "ffmpeg拉流代理无法从ffmpeg cmd中获取到输出格式");