[TYPO3-mvc] Using own renderer fails since TYPO 4.6

[Armin Vieweg]

Hello,

with the version 4.6 much changes of fluid has been made, which makes  
fluid much faster!

I used in an extension an own renderer, which I have created so:

     /**
      * Makes and returns a fluid template object
      *
      * @return Tx_Fluid_View_TemplateView the fluid template object
      */
     protected function makeFluidTemplateObject() {
         /** @var Tx_Fluid_View_TemplateView $fluidTemplate  */
         $fluidTemplate =  
t3lib_div::makeInstance('Tx_Fluid_View_TemplateView');

         // Set controller context
         $controllerContext = $this->buildControllerContext();
         $controllerContext->setRequest($this->request);
         $fluidTemplate->setControllerContext($controllerContext);

         return $fluidTemplate;
     }


I use this $fluidTemplate later to assign templates, variables and render  
it:

    /**
      * Gets the mail message
      *
      * @param mixed $registration model to give to template
      * @param string $templatePath path of fluid template
      *
      * @return string The rendered fluid template (HTML or plain text)
      */
     public function getMailMessage($registration, $templatePath) {
         $mailTemplate = t3lib_div::getFileAbsFileName($templatePath);
         if (!file_exists($mailTemplate)) {
             throw new Exception('Mail template (' . $mailTemplate . ') not  
found. ');
         }
         $this->fluidTemplate->setTemplatePathAndFilename($mailTemplate);

         // Assign variables
         $this->fluidTemplate->assign('registration', $registration);
         $this->fluidTemplate->assign('settings', $this->settings);

         return $this->fluidTemplate->render();
     }

Everything works, except the ->render() call. I get an error 500 without  
any specified exception.

I hope someone has an idea. Thanks in advance!
~Armin