update

wp-content/plugins/youtube-feed-pro/vendor/smashballoon/customizer/app/Container.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace Smashballoon\Customizer;
+
+/** @internal */
+class Container
+{
+    public static $container;
+    /**
+     * @return \DI\Container
+     */
+    public static function getInstance()
+    {
+        if (self::$container === null) {
+            self::$container = (new \SmashBalloon\YoutubeFeed\Vendor\DI\ContainerBuilder())->build();
+        }
+        return self::$container;
+    }
+}