title: NoMethodError in Admin#index
body: <p>I'm a newbie having an issue with Agile Web Development with Rails 2nd. Ruby verison 1.8.6. The issue started when the book instructed me to put scaffold product in the admin_controller.rb. I removed the line and now i'm getting the following error message.</p>
  
  <p>NoMethodError in Admin#index 
  Showing admin/index.html.erb where line #10 raised: </p>
  
  <p>You have a nil object when you didn't expect it!
  You might have expected an instance of Array.
  The error occurred while evaluating nil.each</p>
  
  <p>Extracted source (around line #10): </p>
  
  <pre><code>7:     &lt;th&gt;Image url&lt;/th&gt;
  8:   &lt;/tr&gt;
  9: 
  10: &lt;% for product in @product %&gt;
  11:   &lt;tr&gt;
  12:     &lt;td&gt;&lt;%=h product.title %&gt;&lt;/td&gt;
  13:     &lt;td&gt;&lt;%=h product.description %&gt;&lt;/td&gt;
  </code></pre>
  
  <p>RAILS_ROOT: C:/InstantRails-2.0-win/rails_apps/depot</p>
  
  <p>Here's the controller information:admin_controller
  class AdminController &lt; ApplicationController
  end</p>
  
  <p>Here's the view information: Views\admin\index.html.erb
      <h1>Listing products</h1></p>
  
  <pre><code>&lt;table&gt;
    &lt;tr&gt;
      &lt;th&gt;Title&lt;/th&gt;
      &lt;th&gt;Description&lt;/th&gt;
      &lt;th&gt;Image url&lt;/th&gt;
    &lt;/tr&gt;
  
  &lt;% for product in @product %&gt;
    &lt;tr&gt;
       &lt;td&gt;&lt;%=h product.title %&gt;&lt;/td&gt;
      &lt;td&gt;&lt;%=h product.description %&gt;&lt;/td&gt;
      &lt;td&gt;&lt;%=h product.image_url %&gt;&lt;/td&gt;
      &lt;td&gt;&lt;%= link_to 'Show', product %&gt;&lt;/td&gt;
      &lt;td&gt;&lt;%= link_to 'Edit', edit_product_path(product) %&gt;&lt;/td&gt;
      &lt;td&gt;&lt;%= link_to 'Destroy', product, :confirm =&gt; 'Are you sure?', :method          =&gt; :delete %&gt;&lt;/td&gt;
        &lt;/tr&gt;
  &lt;% end %&gt;
  &lt;/table&gt;
  
  &lt;br /&gt;
  
  &lt;%= link_to 'New product', new_product_path %&gt;
  </code></pre>
  
  <p>Here's the models information: Models\product.rb
  class Product &lt; ActiveRecord::Base
  end</p>
  
  <p>Any advise?</p>