WKErrorDomain error 4 from WKWebView when calling existing JSFunction

No matter what I do, I can't call this js function successfully without generating error.

<script type="text/javascript">
    function getmessage() {
        //$('#discussion').append('<li>dummy</li>');
    }
    $(function () {
        var chat = $.coection.chatHub;
        chat.client.broadcastMessage = function (message) {
            var encodedMsg = $('<div />').text(message).html();
            $('#discussion').append('<li>' + encodedMsg + '</li>');
        };
        $.coection.hub.start().done(function () {
            $('#sendmessage').click(function () {
                chat.server.send($('#message').val());
            });
        });
    });
</script>

error: WKErrorDomain code; 4

I have made sure that I inherit WKNavigaitonDelegate, set view as it's delegate and calling it from didFinishNavigation

Note that I can execute new js blocks just fine from my swift code with no issues, but when calling that existing function, it doesn't work.