Merge pull request 'bug None/1000 solved' (#34) from bug_in_costs_catalog into main

Reviewed-on: https://nextgenerations-cities.encs.concordia.ca/gitea/CERC/hub/pulls/34

hub/catalog_factories/data_models/cost/fuel.py

@@ -46,7 +46,10 @@ class Fuel:
     Get fixed operational costs depending on the peak power consumed in currency per month per W
     :return: None or float
     """
-    return self._fixed_power/1000
+    if self._fixed_power is not None:
+      return self._fixed_power/1000
+    else:
+      return None
 
   @property
   def variable(self) -> Union[tuple[None, None], tuple[float, str]]: