Fix variable assignment for chatModel in ScenarioExecutionService

src/main/java/com/olympus/hermione/services/ScenarioExecutionService.java

@@ -141,7 +141,8 @@ public class ScenarioExecutionService {
                 scenario.setAiModel(aiModel);
                 scenarioExecution.setScenario(scenario);
             }
-            ChatModel chatModel = createChatModel(aiModel);   
+        
+            chatModel = createChatModel(aiModel);   
         
             scenarioExecutionRepository.save(scenarioExecution);