Is there a reason why you can't obtain a weak reference of an object inside the onUpdate function of a view?

Is there a reason why you can't obtain a weak reference of an object inside the onUpdate function of a view?

class controller {
    var test = "it works";
}

class TestView extends WatchUi.View {

    var controller;
    
    function initialize(controller) { // Passed in as a weak reference here
        self.controller = controller;
        var itWorksHere = controller.get()
        System.println(itWorksHere.test); // print "it works"
        
    }

    function onUpdate(dc) {
        // HERE
        var con = controller.get();
        System.println(con.test); // Causes the error below
        
    }
}

Here is the crash I get

Error: Unexpected Type Error
Details: Failed invoking <symbol>
Stack: 
  - onUpdate() at [Path] 0x100122bf 
Encountered an app crash