Cannot read property ‘top’ of undefined issue in WP? or Gravity Forms?

A gravity forms support rep told me there was an issue with my javascript code but didn’t tell me what was wrong. I looked at the screenshot provided and say an error saying:

“Uncaught TypeError: Cannot read property ‘top’ of undefined”

Here’s the code that I’m using:

    jQuery(function() {

// grab the initial top offset of the navigation
var sticky_navigation_offset_top = jQuery('#second-nav').offset().top;

// our function that decides weather the navigation bar should have "fixed" css position or not.
var sticky_navigation = function(){
    var scroll_top = jQuery(window).scrollTop(); // our current vertical position from the top

    // if we've scrolled more than the navigation, change its position to fixed to stick to top,
    // otherwise change it back to relative
    if (scroll_top > sticky_navigation_offset_top) {
        jQuery('#second-nav').css({ 'left':0, 'position': 'fixed', 'top':0, 'width': '100%', 'z-index': 99999999 });
    } else {
        jQuery('#second-nav').css({ 'position': 'relative' });
    }  
};

// run our function on load
sticky_navigation();

// and run it again every time you scroll
jQuery(window).scroll(function() {
     sticky_navigation();
});

});

I looked at some similar questions but I’m not a js fan 🙁

thanks for the help!

edit:

    $(function() {

    // grab the initial top offset of the navigation
    var second-nav_offset_top = $('#second-nav').offset().top;

    // our function that decides weather the navigation bar should have "fixed" css position or not.
    var second-nav = function(){
    var scroll_top = $(window).scrollTop(); // our current vertical position from the top

    // if we've scrolled more than the navigation, change its position to fixed to stick to top, otherwise change it back to relative
    if (scroll_top > second-nav_offset_top) {
    $('#second-nav').css({ 'position': 'fixed', 'top':0, 'left':0 });
    } else {
    $('#second-nav').css({ 'position': 'relative' });
    }  
    };

    // run our function on load
    second-nav();

    // and run it again every time you scroll
    $(window).scroll(function() {
     second-nav();
    });

    });'