Merge pull request #439 from EreMaijala/rtl-notice-fix

Fix startup notice if rtl_langs is not set.

module/VuFind/src/VuFind/Bootstrapper.php

@@ -342,9 +342,10 @@ class Bootstrapper
             $viewModel = $sm->get('viewmanager')->getViewModel();
             $viewModel->setVariable('userLang', $language);
             $viewModel->setVariable('allLangs', $config->Languages);
-            $rtlLangs = array_map(
-                'trim', explode(',', $config->LanguageSettings->rtl_langs)
-            );
+            $rtlLangs = isset($config->LanguageSettings->rtl_langs)
+                ? array_map(
+                    'trim', explode(',', $config->LanguageSettings->rtl_langs)
+                ) : [];
             $viewModel->setVariable('rtl', in_array($language, $rtlLangs));
         };
         $this->events->attach('dispatch.error', $callback, 10000);
@@ -468,4 +469,4 @@ class Bootstrapper
         };
         $this->events->attach('render.error', $callback, 10000);
     }
-}
+}
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