title: Drupal redirects to /core/install.php when I try to open page including a SQLite query
body: <p>I have a Drupal site on a web server. On one page of the site, I want to print out information from a sqlite database. But if I enter the url to the page, I get redirected to /core/install.php</p>
  <p>I integrated the database into the /sites/defualt/settings.php with the following code:</p>
  <pre><code>$databases['external']['default'] = [
  'driver' =&gt; 'sqlite',
  'database' =&gt; '/gesamtausgabe_2019.sqlite',
  ];
  </code></pre>
  <p>I created a module with the /modules/database_mindmap/src/Controller/database_mindmapController.php:</p>
  <pre><code>&lt;?php
  namespace Drupal\database_mindmap\Controller;
  
  class database_mindmapController{
  public function database_mindmap(){
    return include('visual.php');
  }
  }
  ?&gt;
  </code></pre>
  <p>In the included visual.php I call and query the Database with the folowing code:</p>
  <pre><code>&lt;?php
  //open the database
  \Drupal\Core\Database\Database::setActiveConnection('external');
  $database = \Drupal\Core\Database\Database::getConnection();
  $staticID = '008dd40a-9687-4c84-bbfd-95cf0639e09a';
  $sql = 'SELECT * FROM KnowledgeItem';
  $query = $database-&gt;db_query($sql);
  $result = array($query);
  
  while($row = $result) {
  if (strpos($row['StaticIDs'], $staticID) !== false){
    $pagerange_all = explode(&quot; &quot;,$row['PageRange']);
    $text = &quot;&lt;h4&gt;&quot;.$row['CoreStatement'].&quot;&lt;/h4&gt;&quot;.$row['Text'].&quot;&lt;br&gt;&lt;br&gt;&lt;i&gt;Seitenzahl: &quot;.$pagerange_all[9].&quot; &quot;.$pagerange_all[11].&quot;&lt;/i&gt;&quot;;
    echo $text;
  }
  }
  // close the database connection
  Drupal\Core\Database\Database::setActiveConnection();
  
  ?&gt;
  </code></pre>
  <p>So for some strange reason, everytime I call the module with /database/mindmap I get redirected to /core/install.php</p>
  <p>Thanks for any help!</p>