fixed exception when new flagset detected

Author: chillaq

splitio/storage/inmemmory.py

@@ -92,6 +92,8 @@ def remove_feature_flag_to_flag_set(self, flag_set, feature_flag):
         :param feature_flag: feature flag name
         :type feature_flag: str
         """
+        _LOGGER.debug("remove_feature_flag_to_flag_set")
+        _LOGGER.debug(flag_set)
         with self._lock:
             if self.flag_set_exist(flag_set):
                 self.sets_feature_flag_map[flag_set].remove(feature_flag)
@@ -200,7 +202,7 @@ def _remove_from_flag_sets(self, feature_flag):
         if feature_flag.sets is not None:
             for flag_set in feature_flag.sets:
                 self.flag_set.remove_feature_flag_to_flag_set(flag_set, feature_flag.name)
-                if len(self.flag_set.get_flag_set(flag_set)) == 0 and not self.flag_set_filter.should_filter:
+                if self.is_flag_set_exist(flag_set) and len(self.flag_set.get_flag_set(flag_set)) == 0 and not self.flag_set_filter.should_filter:
                     self.flag_set.remove_flag_set(flag_set)
 
     def get_feature_flags_by_sets(self, sets):