How to hide UpdatePanel AJAX and JavaScript errors from FireFox console in ASP.Net

ok the code was which i did : 

function ShowMenu(control, e) {
    try {
        var posx = e.clientX + window.pageXOffset + 'px'; //Left Position of Mouse Pointer
        var posy = e.clientY + window.pageYOffset + 'px'; //Top Position of Mouse Pointer
        document.getElementById(control).style.position = 'absolute';
        document.getElementById(control).style.display = 'inline';
        document.getElementById(control).style.left = posx;
        document.getElementById(control).style.top = posy;
    } catch (err) {

    }
}

function HideMenu(control) {
    try {
        document.getElementById(control).style.display = 'none';
    } catch (err) {

    }

}

then i also used yours suggestion which was :

var prm = Sys.WebForms.PageRequestManager.getInstance();
if (prm != null) {
    prm.add_endRequest(function (sender, e) {
        if (sender._postBackSettings.panelsToUpdate != null) {
            if (e.get_error() != null) {
                e.set_errorHandled(true);
            }
        }
    });
};