T3 error in Frontent in Development mode

I have setup a new environment (Ubuntu VM+T3) to start Development.
T3 ist setup as Production Type “Development”.
When using plugin SAV_Charts I get these errors on the frontpage. I am sure it has nothing directly to do with SAV_Charts since the setup is the same as in my Production environment and it works well there.

Can anyone identify where the problem in the setup of the environment could be?

(1/1) #1476107295 TYPO3\CMS\Core\Error\Exception

PHP Warning: Undefined array key "marker." in /var/www/html/averlon.de/av_t3test/public/typo3conf/ext/sav_charts/Classes/Controller/DefaultController.php line 154
in /var/www/html/averlon.de/av_t3test/public/typo3/sysext/core/Classes/Error/ErrorHandler.php line 137


        $message = self::ERROR_LEVEL_LABELS[$errorLevel] . ': ' . $errorMessage . ' in ' . $errorFile . ' line ' . $errorLine;
        if ($errorLevel & $this->exceptionalErrors) {
            throw new Exception($message, 1476107295);

        $message = $this->getFormattedLogMessage($message);

at TYPO3\CMS\Core\Error\ErrorHandler->handleError()
in /var/www/html/averlon.de/av_t3test/public/typo3conf/ext/sav_charts/Classes/Controller/DefaultController.php line 154

        // Sets markers defined by typoscript
        $typoScriptService = GeneralUtility::makeInstance(TypoScriptService::class);
        $typoScriptConfiguration = $typoScriptService->convertPlainArrayToTypoScriptArray($this->getSettings());
        if (is_array($typoScriptConfiguration) && is_array($typoScriptConfiguration['marker.'])) {
            $typoScriptMarkers = $typoScriptConfiguration['marker.'];
            foreach ($typoScriptMarkers as $typoScriptMarkerKey => $typoScriptMarker) {
                if (strpos($typoScriptMarkerKey, '.') === false) {
                    $typoScriptValue = $this->getContentObjectRenderer()->cObjGetSingle($typoScriptMarker, $typoScriptMarkers[$typoScriptMarkerKey . '.']);

at YolfTypo3\SavCharts\Controller\DefaultController->showAction()
in /var/www/html/averlon.de/av_t3test/public/typo3/sysext/extbase/Classes/Mvc/Controller/ActionController.php line 575

        $validationResult = $this->arguments->validate();
        if (!$validationResult->hasErrors()) {
            $this->eventDispatcher->dispatch(new BeforeActionCallEvent(static::class, $this->actionMethodName, $preparedArguments));
            $actionResult = $this->{$this->actionMethodName}(...$preparedArguments);
        } else {
            $actionResult = $this->{$this->errorMethodName}();

at TYPO3\CMS\Extbase\Mvc\Controller\ActionController->callActionMethod()
in /var/www/html/averlon.de/av_t3test/public/typo3/sysext/extbase/Classes/Mvc/Controller/ActionController.php line 492

        $this->view = $this->resolveView();
        if ($this->view !== null && method_exists($this, 'initializeView')) {
        $response = $this->callActionMethod($request);

        return $response;

at TYPO3\CMS\Extbase\Mvc\Controller\ActionController->processRequest()
in /var/www/html/averlon.de/av_t3test/public/typo3/sysext/extbase/Classes/Mvc/Dispatcher.php line 96

                throw new InfiniteLoopException('Could not ultimately dispatch the request after ' . $dispatchLoopCount . ' iterations. Most probably, a @' . IgnoreValidation::class . ' annotation is missing on re-displaying a form with validation errors.', 1217839467);
            $controller = $this->resolveController($request);
            try {
                $response = $controller->processRequest($request);
                if ($response instanceof ForwardResponse) {
                    // The controller action returned an extbase internal Forward response:
                    // Another action should be dispatched.
                    $request = static::buildRequestFromCurrentRequestAndForwardResponse($request, $response);

at TYPO3\CMS\Extbase\Mvc\Dispatcher->dispatch()
in /var/www/html/averlon.de/av_t3test/public/typo3/sysext/extbase/Classes/Mvc/Web/FrontendRequestHandler.php line 46

     * @throws InfiniteLoopException
    public function handleRequest(RequestInterface $request)
        return $this->dispatcher->dispatch($request);

     * This request handler can handle any web request.

There are some more lines but the thread is limited - for good reason!

I am nearly sure there is something on permissions or wrong file content somewhere. But since I am not familiar with PHP I cannot find out.

Help appreciated.
Regards Karl-Heinz

as this comment shows: it is about markers in typoscript.
probably markers which are expected but are not defined.

have you any typoscript which might belong here?
and the classic: have you included the static templates for this extension?

static template is included.

I have used SAV_Charts since years now and I am not aware of any markers to set. Not even any typoscript, since all settings are made via BE.

But I will check again.

in “Production” environment these error messages are also listed in the log. But the FE works.

Since I am new to “Development” environment, where I want to start own Extension Development, it looks to me that all error messages from all PHP-Code will get reported via the FE unless it is solved.
Since SAV_Charts works in “Production” - beside the error messages in the log - the error messages in the FE block me (somehow) to do the next steps in my own extension.
So question for me is how to get rid of them (only the ones from SAV_Charts). O.K. - I could deinstall.