java.lang.NullPointerException changing to Manual tab for groovy code using @ to access an attribute

OS Windows 7

Katalon Studio Version 5.3.0

## Katalon Studio logs:

!ENTRY org.eclipse.jface 4 2 2018-02-13 03:39:45.649
!MESSAGE Problems occurred when invoking code from plug-in: “org.eclipse.jface”.
!STACK 0
java.lang.NullPointerException

## Environment (for Web testing)

none

## Steps to reproduce -

Make a new test case and change to the script tab

def htmlObject = new XmlParser().parseText('<body><a href="someurl">sometext</a></body>')
def activationurl = htmlObject.a.@href.value[0]
println activationurl

## Expected Behavior -

switching to Manual tab should not error as the code runs fine. (although if you have a workaround that’d be good for me too)

## Actual Behavior -

I’ve had it delete the second line of code a couple of times but I generally just get the error message

## Screenshots / Videos