Hi all,
I currently have a few screens set up in Agent app for a custom table we are using, and on one of the screens I want to make an action to add the logged in user to a list field, however am having no luck being able to add any code into the action item at all. 
I'm trying to avoid having to initialise input variables etc as per what the error is suggesting because I'm expecting when that happens the user will be presented a screen to fill in, when all I want is for them to be able to swipe on a record and tap the action. I have a similar action that just closes the record, but that one is a straightforward update action and I can't do an update action on a list field, hence the need for scripting (unless someone has an alternative).
edit: I know the code in the screenshot below is not necessarily correct to be used in mobile app builder, but I have tried to comment out everything except the info message or just a gs.log message and that is also failing.
