Uncaught SyntaxError: Unexpected token F in JSON at position 1

/* 
===================================================== 
Field Search - Сортировка новостей пользователями по доп полям и не только 
----------------------------------------------------- 
Автор : Gameer 
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Site : http://gameer.name/ 
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Copyright (c) 2016 Gameer 
===================================================== 
Данный код защищен авторскими правами 
*/ 
var back_url = window.location.pathname; 
var back_title = document.title; 
var back_speedbar = document.getElementById("dle-speedbar"); 
$(function(){ 
	$('body').on('click', '[data-fieldsearch=submit]', function() { 
		var $filter_field = $(this).closest('form').serialize(); 
		window.history.replaceState(null, null, "/"); 
		ShowLoading("Ищем... ищем... ищем..."); 
		$.post(dle_root + "engine/ajax/field_search.php", { form_field : $filter_field }, function(data){ 
			if(data) 
			{ 
				window.history.replaceState(null, null, "/"); 
				var content = jQuery.parseJSON( data ); 
				$("#dle-content1").remove(); 
				$("#dle-content").css("display", "none"); 
				$("#dle-content").before("<div id=\"dle-content1\">" + content.content + "</div>"); 
				window.history.replaceState(null, null, content.url); 
			} 
		}); 
		HideLoading(""); 
		return false; 
	}); 
	$('body').on('click', '.field_search_nav > a', function() { 
		var $filter_field = $( this ).attr("href"); 
		window.history.replaceState(null, null, "/"); 
		ShowLoading("Ищем... ищем... ищем..."); 
		$.post(dle_root + "engine/ajax/field_search.php", { form_field : $filter_field, filter_nav : 1 }, function(data){ 
			if(data) 
			{ 
				window.history.replaceState(null, null, "/"); 
				var content = jQuery.parseJSON( data ); 
				document.title = content.meta_title; 
				$("#dle-speedbar").html(content.speedbar); 
				$("#dle-content1").remove(); 
				$("#dle-content").css("display", "none"); 
				$("#dle-content").before("<div id=\"dle-content1\">" + content.content + "</div>"); 
				window.history.replaceState(null, null, content.url); 
			} 
		}); 
		HideLoading(""); 
		return false; 
	}); 
	$( "[data-filtertriger=fieldseacrh]" ).change(function() { 
		var $filter_field = $( this ).serialize(); 
		window.history.replaceState(null, null, "/"); 
		ShowLoading("Ищем... ищем... ищем..."); 
		$.post(dle_root + "engine/ajax/field_search.php", { form_field : $filter_field }, function(data){ 
			if(data) 
			{ 
				window.history.replaceState(null, null, "/"); 
				var content = jQuery.parseJSON( data ); 
				$("#dle-content1").remove(); 
				$("#dle-content").css("display", "none"); 
				$("#dle-content").before("<div id=\"dle-content1\">" + content.content + "</div>"); 
				window.history.replaceState(null, null, content.url); 
			} 
		}); 
		HideLoading(""); 
	}); 
	 
	$('body').on('click', '[data-fieldsearch="reset"]', function() { 
		window.history.replaceState(null, null, back_url); 
		ShowLoading("Секунду..."); 
		document.title = back_title; 
		$("#dle-speedbar").html(back_speedbar); 
		$('[data-filtertriger=fieldseacrh] input[type="text"]').each(function(i){ 
			if($(this).attr('name') != undefined) 
			{ 
				if($(this).attr('name').indexOf('r-') + 1) 
				{ 
					var slider = $(this).data("ionRangeSlider"); 
					slider.update({ 
						from: slider.options.min, 
						to: slider.options.max 
					}); 
				} 
				else 
				{ 
					$(this).val(''); 
				} 
			} 
		}); 
		$('[data-filtertriger=fieldseacrh] select').each(function(i){ 
			$(this).children('option').each(function(n){ 
				$(this).attr('selected', false); 
			}); 
		}); 
 
		$('[data-filtertriger=fieldseacrh] input[type="radio"], [data-filtertriger=fieldseacrh] input[type="checkbox"]').each(function(i){ 
			$(this).attr('checked', false); 
		}); 
		$("#dle-content1").remove(); 
		$("#dle-content").css("display", "block"); 
		HideLoading(""); 
		return false; 
	}); 
});