Update to TYPO3 8.7 LTS

web/typo3conf/ext/ep_theme/Classes/DataProcessing/SliderProcessor.php

@@ -79,7 +79,11 @@ class SliderProcessor implements DataProcessorInterface
             foreach ($slides as $slide)
             {
                 $processedData['slides'][$slide['uid']] = $slide;
-                $processedData['slides'][$slide['uid']]['image'] = $fileRepository->findByRelation('tx_eptheme_domain_model_slide', 'images', $slide['uid']);
+                $processedData['slides'][$slide['uid']]['image'] = $fileRepository->findByRelation(
+                    'tx_eptheme_domain_model_slide',
+                    'images',
+                    $slide['uid']
+                );
             }
         }