Correct mistakes in _return_empty and _return_impact

Author: luseverin

climada/engine/impact_calc.py

@@ -240,8 +240,8 @@ def _return_impact(self, imp_mat_gen, save_mat):
             self.exposures, self.hazard, at_event, eai_exp, aai_agg, imp_mat
         )
         if isinstance(self.hazard, HazardForecast):
-            return ImpactForecast().from_impact(
-                impact, self.hazard.ensemble_member, self.hazard.lead_time
+            return ImpactForecast.from_impact(
+                impact, self.hazard.lead_time, self.hazard.member
             )  # return ImpactForecast object
         else:
             return (
@@ -275,8 +275,8 @@ def _return_empty(self, save_mat):
             self.exposures, self.hazard, at_event, eai_exp, aai_agg, imp_mat
         )
         if isinstance(self.hazard, HazardForecast):
-            return ImpactForecast().from_impact(
-                impact, self.hazard.ensemble_member, self.hazard.lead_time
+            return ImpactForecast.from_impact(
+                impact, self.hazard.lead_time, self.hazard.member
             )  # return ImpactForecast object
         else:
             return (