Fix data tracker

When no valid networks are found in an iteration of the supply systems optimisation the tracker (tracking optimal networks) would not be able store anything and run into an error. This changes fixes this edge-case.

cea/optimization_new/helpercalsses/optimization/tracker.py

@@ -53,6 +53,7 @@ def add_candidate_individual(self, candidate_individual):
         connectivity vectors have been analysed.
         """
         network_ids = [network.identifier for network in candidate_individual.networks]
+        networks_with_supsys = list(candidate_individual.supply_systems.keys())
         network_graphs = {network.identifier: network
                           for network in candidate_individual.networks}
         supsys_structures = {network_id: supply_systems[0].structure
@@ -65,7 +66,8 @@ def add_candidate_individual(self, candidate_individual):
             {network_id: {'network_graph': network_graphs[network_id],
                           'supsys_structure': supsys_structures[network_id],
                           'supsys_individuals': supsys_individuals[network_id]}
-             for network_id in network_ids}
+             for network_id in network_ids
+             if network_id in networks_with_supsys}
 
     def set_current_individual(self, connectivty_vector):
         """ Update the current connectivity vector which is being evaluated. """