fixed a bug when there is no data for netpositions

Author: fboerman

entsoe/entsoe.py

@@ -23,7 +23,7 @@
 warnings.filterwarnings('ignore', category=XMLParsedAsHTMLWarning)
 
 __title__ = "entsoe-py"
-__version__ = "0.6.10"
+__version__ = "0.6.11"
 __author__ = "EnergieID.be, Frank Boerman"
 __license__ = "MIT"
 
@@ -1169,6 +1169,8 @@ def query_net_position(self, country_code: Union[Area, str],
         text = super(EntsoePandasClient, self).query_net_position(
             country_code=area, start=start, end=end, dayahead=dayahead)
         series = parse_netpositions(text, resolution=resolution)
+        if len(series) == 0:
+            raise NoMatchingDataError
         series = series.tz_convert(area.tz)
         series = series.truncate(before=start, after=end)
         return series

entsoe/parsers.py

@@ -69,7 +69,8 @@ def parse_netpositions(xml_text, resolution):
         # take the absolute value and correct for region
         #TODO: possible change this or remove this warning after helpdesk got back to me
         series_all.append(factor*series.abs())
-
+    if len(series_all) == 0:
+        return pd.Series()
     series_all = pd.concat(series_all).sort_index()
     return series_all