fix: Kubelink Requests getting Failed for gRPC method GetAppDetails (#5012)

* fixed

* code review comments

Author: ShashwatDadhich

api/restHandler/app/appList/AppListingRestHandler.go

@@ -980,6 +980,10 @@ func (handler AppListingRestHandlerImpl) getAppDetails(ctx context.Context, appI
 // TODO: move this to service
 func (handler AppListingRestHandlerImpl) fetchResourceTree(w http.ResponseWriter, r *http.Request, appId int, envId int, acdToken string, cdPipeline *pipelineConfig.Pipeline) (map[string]interface{}, error) {
 	var resourceTree map[string]interface{}
+	if !cdPipeline.DeploymentAppCreated {
+		handler.logger.Infow("deployment for this pipeline does not exist", "pipelineId", cdPipeline.Id)
+		return resourceTree, nil
+	}
 	if len(cdPipeline.DeploymentAppName) > 0 && cdPipeline.EnvironmentId > 0 && util.IsAcdApp(cdPipeline.DeploymentAppType) {
 		// RBAC enforcer Ends
 		query := &application2.ResourcesQuery{