element.$server is undefined when passing data from java to javascript in vaadin 14

I'm trying to interact between Vaadin and amcharts. Basically I need to draw a map using amcharts libraries, and when I click on the map I need to send back information about the click to Java. My problem is that I can't figure out how to properly interact between the two, with the documentation showing very simple examples.

In the vaadin docs it shows an example like:

getElement().executeJS("jsMethodName($0)", getElement());

and then to send back data to Java:

element.$server.javaMethodName(args);

My problem is that I can send from Java to JS correctly, and the element is loaded correctly. But when I do element.$server.javaMethodName(), element.$server is always undefined. I don't understand if I'm missing something or if I dind't understand the correct way to use this.

This is my Java method:

    @ClientCallable
    private void clickBullet(String area) {

        log.error("Clicked area: " + area);
    }

and this is the call from JS:

function clickBullet(name, element) {
        if(element !== null){
            element.$server.clickBullet(name);
        }
        else {
            console.log("element is null");
        }

    }

Note that element is not null, it is correct. What am I doing wrong?