diff --git a/core/lib/Drupal/Core/Asset/LibraryDiscoveryParser.php b/core/lib/Drupal/Core/Asset/LibraryDiscoveryParser.php
index 4512752..ec437ff 100644
--- a/core/lib/Drupal/Core/Asset/LibraryDiscoveryParser.php
+++ b/core/lib/Drupal/Core/Asset/LibraryDiscoveryParser.php
@@ -384,7 +384,7 @@ protected function applyLibrariesOverride($libraries, $extension) {
         }
       }
     }
-    
+
     return $libraries;
   }
 
diff --git a/core/lib/Drupal/Core/Theme/ThemeInitialization.php b/core/lib/Drupal/Core/Theme/ThemeInitialization.php
index bc38902..1d908bb 100644
--- a/core/lib/Drupal/Core/Theme/ThemeInitialization.php
+++ b/core/lib/Drupal/Core/Theme/ThemeInitialization.php
@@ -225,7 +225,7 @@ public function getActiveTheme(Extension $theme, array $base_themes = []) {
    */
   protected function getExtensions() {
     if (!isset($this->extensions)) {
-      $this->extensions = array_merge($this->moduleHandler->getModuleList(), $this->themeHandler->listInfo());
+      $this->extensions = array_merge($this->moduleHandler->getModuleList(),  $this->themeHandler->listInfo());
     }
     return $this->extensions;
   }
@@ -264,7 +264,7 @@ protected function resolveStyleSheetPlaceholders($css_file) {
    * @param \Drupal\Core\Extension\Extension[] $base_themes
    *   An array of base themes.
    *
-   * @return string
+   * @return string[]
    *
    * @todo Remove in Drupal 9.0.x
    */