Web\Session: implement lazy loading

fixes #7055

library/Icinga/Application/Web.php

@@ -13,8 +13,6 @@ use Icinga\Logger\Logger;
 use Icinga\Web\Request;
 use Icinga\Web\Response;
 use Icinga\Web\View;
-use Icinga\Web\Session\Session as BaseSession;
-use Icinga\Web\Session;
 use Icinga\User;
 use Icinga\Util\Translator;
 use Icinga\Util\DateTimeFactory;
@@ -59,13 +57,6 @@ class Web extends ApplicationBootstrap
      */
     private $request;
 
-    /**
-     * Session object
-     *
-     * @var BaseSession
-     */
-    private $session;
-
     /**
      * User object
      *
@@ -92,7 +83,6 @@ class Web extends ApplicationBootstrap
             ->setupErrorHandling()
             ->loadConfig()
             ->setupResourceFactory()
-            ->setupSession()
             ->setupUser()
             ->setupTimezone()
             ->setupLogger()
@@ -172,7 +162,6 @@ class Web extends ApplicationBootstrap
 
         $this->setupFrontController();
         $this->setupViewRenderer();
-
         return $this;
     }
 
@@ -192,17 +181,6 @@ class Web extends ApplicationBootstrap
         return $this;
     }
 
-    /**
-     * Initialize a session provider
-     *
-     * @return  self
-     */
-    private function setupSession()
-    {
-        $this->session = Session::create();
-        return $this;
-    }
-
     /**
      * Inject dependencies into request
      *

library/Icinga/Web/Session.php

@@ -47,7 +47,7 @@ class Session
     public static function getSession()
     {
         if (self::$session === null) {
-            throw new ProgrammingError('No session created yet');
+            self::create();
         }
 
         return self::$session;