Fix 500 error when creating from the template and the provider is None (#2591)

api/controllers/console/app/app.py

             available_models_names = [f'{model.provider.provider}.{model.model}' for model in available_models]
             provider_model = f"{model_config_dict['model']['provider']}.{model_config_dict['model']['name']}"
             if provider_model not in available_models_names:
-                model_manager = ModelManager()
-                model_instance = model_manager.get_default_model_instance(
-                    tenant_id=current_user.current_tenant_id,
-                    model_type=ModelType.LLM
-                )
-
-                if not model_instance:
+                if not default_model_entity:
                     raise ProviderNotInitializeError(
                         "No Default System Reasoning Model available. Please configure "
                         "in the Settings -> Model Provider.")
                 else:
-                    model_config_dict["model"]["provider"] = model_instance.provider
-                    model_config_dict["model"]["name"] = model_instance.model
+                    model_config_dict["model"]["provider"] = default_model_entity.provider
+                    model_config_dict["model"]["name"] = default_model_entity.model
 
             model_configuration = AppModelConfigService.validate_configuration(
                 tenant_id=current_user.current_tenant_id,