fixed

Closes #3399960

splitting.install

@@ -17,12 +17,18 @@ function splitting_requirements($phase) {
   /** @var Drupal\Core\Asset\LibraryDiscovery $library_discovery */
   $library_discovery = \Drupal::service('library.discovery');
   $library_splitting = $library_discovery->getLibraryByName('splitting', 'splitting.js');
-  $library_exists_js = file_exists(DRUPAL_ROOT . '/' . $library_splitting['js'][0]['data']);
+
+  // Check if $library_splitting is an array before accessing its elements.
+  if (is_array($library_splitting) && isset($library_splitting['js'][0]['data'])) {
+    $library_exists_js = file_exists(DRUPAL_ROOT . '/' . $library_splitting['js'][0]['data']);
+  } else {
+    $library_exists_js = false;
+  }
 
   switch ($phase) {
     case 'install':
       if (!$library_exists_js) {
-        $description = t('The Splitting.js library is missing. Please <a href=":downloadUrl" rel="external" target="_blank">Download the library</a> and and extract to /libraries/splitting directory.', [
+        $description = t('The Splitting.js library is missing. Please <a href=":downloadUrl" rel="external" target="_blank">Download the library</a> and extract it to the /libraries/splitting directory.', [
           ':downloadUrl' => SPLITTING_DOWNLOAD_URL,
         ]);
         $requirements['splitting']['description'] = $description;
@@ -31,8 +37,8 @@ function splitting_requirements($phase) {
         \Drupal::messenger()->addWarning($description);
       }
       break;
-
     case 'runtime':
+    
 
       // Show the status of the library in the status report section.
       if ($library_exists_js) {