title: Page has a @IonicPage decorator, but it does not have a corresponding "NgModule"
body: <p>I was working on page navigation in Ionic. After using <code>ionic serve</code>, I got this error:</p>
  
  <p><code>The Page with .ts extension has a @IonicPage decorator, but it does  not have a corresponding "NgModule"</code>.  </p>
  
  <p>Can anyone explain why I am getting this error.</p>