How to do proper error handling in REST WebServices?

Summary:

I want to do proper error handling with REST WebServices and looking at the documentation I found that:

def conn = adf.webServices.GetTicketForAccount

try{

// Provide Account Id for which user wants to retrieve trouble ticket

def tickets = conn.GET("6637911")

println("Headers:"+conn.responseHTTPHeaders)

println("Status:"+conn.statusCode)

println("Output:"+tickets)

}catch(Exception e){

println("Headers:"+conn.responseHTTPHeaders)

println("Status:"+conn.statusCode)

println("Error:"+e)

}

But that when I call for example a POST Service Request with a wrong value it returns to me Bad Request 404 and it enters the catch exception but the variables are all null/empty.

responseHTTPHeaders is null