#91 -- fix time series tendency estimation

src/main/java/ru/ulstu/extractor/ts/service/TimeSeriesService.java

@@ -128,7 +128,8 @@ public class TimeSeriesService {
         if (ts != null && ts.getValues().size() > MIN_TIME_SERIES_LENGTH) {
             JSONObject response = httpService.post(TIME_SERIES_TENDENCY_URL, new JSONObject(new JsonTimeSeries(normalizeTimeSeries(ts))));
             LOG.debug("Успешно отправлен на сервис сглаживания");
-            if (response.has("response") && response.getString("response").equals("empty")) {
+            if (response.has("response") && response.getString("response").equals("empty")
+                    || !response.has("timeSeries")) {
                 return DEFAULT_TIME_SERIES_TENDENCY;
             }
             JSONArray jsonArray = response.getJSONObject("timeSeries").getJSONArray("values");