Thanks for your respose , I am able to fetch error message in my Test flow
In my acutal flow "Start and wait for approval" is inside "Apply for each" loop which is inside "Scope" (Standard workflow execution) . Following is the screenshot

Now , In the Scope (catch) , result('Stadard_workflow_execution') provides the following error details
[{
"name":"Check_Input_option",
"inputs":{"expressionResult":true},
"startTime":"2023-03-10T17:35:57.1195822Z",
"endTime":"2023-03-10T17:37:08.9050632Z",
"code":"ActionFailed","status":"Failed",
"error":{"code":"ActionFailed","message":"An action failed. No dependent actions succeeded."
}}]
Is there a way , I can fetch the error message "The workflow action 'Start_and_wait_for_an_approval' timed out while waiting for webhook callback." ?