title: Laravel group routing issue
body: <p>Laravel routing issue while using the contrain on parameter with routing without  <code>-&gt;where('id', '[0-9]+');</code> working but I need to add this.</p>
  
  <pre><code>Route::group(['prefix' =&gt; '/{id}'], function () { 
      Route::post('/edit', 'User\InstituteController@editInstitute');
  })-&gt;where('id', '[0-9]+');
  </code></pre>
  
  <p>Which causes the following error</p>
  
  <blockquote>
    <p>Call to a member function where() on a non-object</p>
  </blockquote>