title: Value cannot be null or empty. Parameter name linkText
body: <p>I have a project that similar on site in "asp.net MVC for professional" book,
  so i have a problem with navigation bar, problem in view.</p>
  
  <p>the text of error is:
  Value cannot be null or empty.
  Имя параметра: linkText</p>
  
  <pre><code>@foreach (var link in Model)
    {
     @Html.RouteLink(link, new
    {
        controller = "Profile"
  
  ,
  </code></pre>
  
  <p>I understand that problem in link, but I have no idea how to fix it.</p>
  
  <p>below code of controllers and view.
  <strong>Menu.cshtml</strong></p>
  
  <pre><code>@model IEnumerable&lt;string&gt;
  
      @Html.ActionLink("List", "Profile")
      @foreach (var link in Model)
      {
          @Html.RouteLink(link, new
      {
          controller = "Profile",
          action = "List",
          category = link,
          page = 1
      })
      }
  </code></pre>
  
  <p><strong>NavController</strong></p>
  
  <pre><code>using System;
  using System.Collections.Generic;
  using System.Linq;
  using System.Web;
  using System.Web.Mvc;
  using HoboAnimal.Domain.Abstract;
  
  
  namespace HoboAnimal.WebUI.Controllers
  {
      public class NavController : Controller
      {
          private IProfileRepository repository;
          public NavController(IProfileRepository repo)
          {
              repository= repo;
          }
          public PartialViewResult Menu(){ 
  
              IEnumerable&lt;string&gt; categories = repository.Profiles.
                  Select(x =&gt; x.Category).
                  Distinct().
                  OrderBy(x =&gt; x);
              return PartialView(categories);
          }
      }
  }
  </code></pre>
  
  <p><strong>Layout</strong></p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
      &lt;meta charset="utf-8" /&gt;
      &lt;meta name="viewport" content="width=device-width" /&gt;
      &lt;title&gt;@ViewBag.Title&lt;/title&gt;
      &lt;link href="~/Content/Site.css" type="text/css" rel="stylesheet" /&gt;
  &lt;/head&gt;
  &lt;body&gt;
      &lt;div id="header"&gt;
  
      &lt;/div&gt;
      &lt;div id="categories"&gt;
          @{Html.Action("Menu","Nav");}
      &lt;/div&gt;
      &lt;div id="content"&gt;
          @RenderBody()
      &lt;/div&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>Thank you</p>