jQuery error help

Having a problem with one of the functions in my form.js file.  For some reason it breaks alot of js functionality on the site, such as menus, columns etc.

forms.js

jQuery(document).ready(setupForms);

function setupForms(){
	
	if(jQuery(".wp-block-forms").size() === 0) return false;
	
	jQuery('#user-category').on('change', function(){
		
		var current = jQuery(this);
		var value = current.val();
		var category = jQuery('option[value="'+value+'"]', current).attr('data-cat');
		var primaryProject = jQuery('#primary-project');
		
		primaryProject.val(jQuery("option:first", primaryProject).val());

		jQuery('option.active', primaryProject).removeClass('active');
		jQuery('option[data-cat="'+category+'"]', primaryProject).addClass('active');
		
	});
	
	if(jQuery("#combine-name").size() === 0) return false;
	
	var nameFields = jQuery('#first-name, #last-name');
	
	nameFields.on('keyup', function(){
		jQuery('#combine-name').val(jQuery('#first-name').val() + ' ' + jQuery('#last-name').val());
	});
	
	jQuery('#full_name').on('blur', function() {
		var result = jQuery('#full_name').val().split(/(?<=^\S+)\s/);
	  jQuery('#first-name').val(result[0]);
	  jQuery('#last-name').val(result[1]);
	});

	//Function for passing State value through hidden field, based on phone number area code.
	jQuery('#phone').on('blur', function () {
        var pe = jQuery(this);
        var pNumber = pe.val();
        if (pNumber.length < 3) {
            return;
        }

        var areaCode = pNumber.substr(0, 3);
        jQuery('#areacode').val(getState(areaCode));
	});
	
	//Function for passing State value through hidden field, based on phone number area code.
	jQuery('#phone').on('blur', function () {
        var peCountry = jQuery(this);
        var pNumberCountry = peCountry.val();
        if (pNumberCountry.length < 3) {
            return;
        }

        var areaCodeCountry = pNumberCountry.substr(0, 3);
        jQuery('#areacodeCountry').val(getCountry(areaCodeCountry));
    });

 }

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Now if i take out the split names functionality, and my file looks like this,  everything works again (except for the split the full name into first/last name which i took out. )

jQuery(document).ready(setupForms);

function setupForms(){
	
	if(jQuery(".wp-block-forms").size() === 0) return false;
	
	jQuery('#user-category').on('change', function(){
		
		var current = jQuery(this);
		var value = current.val();
		var category = jQuery('option[value="'+value+'"]', current).attr('data-cat');
		var primaryProject = jQuery('#primary-project');
		
		primaryProject.val(jQuery("option:first", primaryProject).val());

		jQuery('option.active', primaryProject).removeClass('active');
		jQuery('option[data-cat="'+category+'"]', primaryProject).addClass('active');
		
	});
	
	if(jQuery("#combine-name").size() === 0) return false;
	
	var nameFields = jQuery('#first-name, #last-name');
	
	nameFields.on('keyup', function(){
		jQuery('#combine-name').val(jQuery('#first-name').val() + ' ' + jQuery('#last-name').val());
	});

	//Function for passing State value through hidden field, based on phone number area code.
	jQuery('#phone').on('blur', function () {
        var pe = jQuery(this);
        var pNumber = pe.val();
        if (pNumber.length < 3) {
            return;
        }

        var areaCode = pNumber.substr(0, 3);
        jQuery('#areacode').val(getState(areaCode));
	});
	
	//Function for passing State value through hidden field, based on phone number area code.
	jQuery('#phone').on('blur', function () {
        var peCountry = jQuery(this);
        var pNumberCountry = peCountry.val();
        if (pNumberCountry.length < 3) {
            return;
        }

        var areaCodeCountry = pNumberCountry.substr(0, 3);
        jQuery('#areacodeCountry').val(getCountry(areaCodeCountry));
    });

 }

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Can anybody see why this would be killing functionality on the site?
jQuery('#full_name').on('blur', function() {
            var result = jQuery('#full_name').val().split(/(?<=^\S+)\s/);
        jQuery('#first-name').val(result[0]);
        jQuery('#last-name').val(result[1]);
      });