Update MD_STD_CACHE to reload error pages

MD_STD_CACHE.php

@@ -60,7 +60,7 @@ public static function serve_page_through_redis_cache(string $redisKey, int $exp
 
             if (($redisResult = $redis->get($redisKey))) {
 
-                if (strlen($redisResult) > 3) {
+                if (strlen($redisResult) > 3 and strpos($redisResult, ' id="errorPage"') === false) {
                     $redis->close();
                     return $redisResult;
                 }