Bug fix save_as_cmdows function

Former-commit-id: 78e93892af9c81d4ce1c09392782db764f35f6a4

pyKADMOS/sample/graph.py

@@ -3130,9 +3130,10 @@ class KadmosGraph(nx.DiGraph):
                   str(graph_problem_formulation.get('allow_unconverged_couplings')).lower())
             # Create problemDefinition/problemFormulation/doeSettings
             cmdows_doe_settings = Child(cmdows_problem_formulation, 'doeSettings')
-            for graph_doeSettingKey, graph_doeSettingValue in graph_problem_formulation['doe_settings'].iteritems():
-                if graph_doeSettingKey != 'doe_table':
-                    Child(cmdows_doe_settings, make_camel_case(graph_doeSettingKey), graph_doeSettingValue)
+            if graph_problem_formulation.get('doe_settings') is not None:
+                for graph_doeSettingKey, graph_doeSettingValue in graph_problem_formulation['doe_settings'].iteritems():
+                    if graph_doeSettingKey != 'doe_table':
+                        Child(cmdows_doe_settings, make_camel_case(graph_doeSettingKey), graph_doeSettingValue)
             # Create problemDefinition/problemRoles
             cmdows_problem_roles = Child(cmdows_problem_definition, 'problemRoles')
             # Create problemDefinition/problemRoles/parameters