title: invalid value for Integer(): "''" in pagination of rails 4
body: <p>I get a pagination error like as follows.
  invalid value for Integer(): "''"
  In my controller I use the code:</p>
  
  <p><code>@articles = Article.all.paginate(page: params[:page], per_page: 5)</code> </p>
  
  <p>In the index method. What is the error?</p>