Merge branch '5.4' into 6.0

* 5.4:
  [Mailer] Fix string-cast of exceptions thrown by authenticator in EsmtpTransport
  [Cache] fix error handling
  [Security] Fix wrong authenticator class in debug logs
  43460: add missing validator component turkish translations
  Fix generic type for FormErrorIterator

Author: derrabus

Transport/Smtp/EsmtpTransport.php

@@ -179,7 +179,7 @@ private function handleAuth(array $modes): void
                 }
 
                 // keep the error message, but tries the other authenticators
-                $errors[$authenticator->getAuthKeyword()] = $e;
+                $errors[$authenticator->getAuthKeyword()] = $e->getMessage();
             }
         }