refactor: add return types

Author: kenjis

system/Cache/FactoriesCache.php

@@ -40,7 +40,7 @@ public function save(string $component): void
         $this->cache->save($this->getCacheKey($component), $data, 3600 * 24);
     }
 
-    private function getCacheKey(string $component)
+    private function getCacheKey(string $component): string
     {
         return 'FactoriesCache_' . $component;
     }

system/Config/Factories.php

@@ -474,7 +474,7 @@ public static function getComponentInstances(string $component): array
      *
      * @internal For caching only
      */
-    public static function setComponentInstances(string $component, array $data)
+    public static function setComponentInstances(string $component, array $data): void
     {
         static::$aliases[$component] = $data['aliases'];
         self::$instances[$component] = $data['instances'];