Avoid type errors

public/typo3conf/ext/ep_products/Classes/Service/FilterService.php

@@ -8,6 +8,7 @@ use Symfony\Component\OptionsResolver\Options;
 use Symfony\Component\OptionsResolver\OptionsResolver;
 use TYPO3\CMS\Core\SingletonInterface;
 use TYPO3\CMS\Core\Utility\GeneralUtility;
+use TYPO3\CMS\Extbase\Configuration\ConfigurationManager;
 use TYPO3\CMS\Extbase\Configuration\ConfigurationManagerInterface;
 
 class FilterService implements SingletonInterface
@@ -15,19 +16,6 @@ class FilterService implements SingletonInterface
     public const DURATION_SHORT = 4;
     public const DURATION_LONG = 5;
 
-    /**
-     * @var ConfigurationManagerInterface
-     */
-    protected $configurationManager;
-
-    /**
-     * @param ConfigurationManagerInterface $configurationManager
-     */
-    public function __construct(ConfigurationManagerInterface $configurationManager)
-    {
-        $this->configurationManager = $configurationManager;
-    }
-
     public function getNormalizedFilterSettings(array $filterSettings = [], array $forcedConceptUids = []): array
     {
         $optionsResolver = new OptionsResolver();
@@ -323,8 +311,9 @@ class FilterService implements SingletonInterface
 
     protected function getTypoScriptSettings(): array
     {
-        $settings = $this
-            ->configurationManager
+        /** @var ConfigurationManager $configurationManager */
+        $configurationManager = GeneralUtility::makeInstance(ConfigurationManager::class);
+        $settings = $configurationManager
             ->getConfiguration(ConfigurationManagerInterface::CONFIGURATION_TYPE_FULL_TYPOSCRIPT);
 
         return $settings['plugin.']['tx_epproducts.']['settings.'];

public/typo3conf/ext/ep_products/Classes/Service/ProductDataService.php

@@ -77,11 +77,15 @@ class ProductDataService implements SingletonInterface
      *
      * @return array
      */
-    public function getTeaser(array $filterSettings): array
+    public function getTeaser(array $filterSettings): ?array
     {
         $teaserData = $this->productRepository->getTeasers($filterSettings);
         $teasers = $this->preprocessTeasergroup($teaserData);
 
+        if (0 === count($teasers)) {
+            return null;
+        }
+
         return reset($teasers);
     }