updated composer

vendor/symfony/string/UnicodeString.php

@@ -359,6 +359,10 @@ class UnicodeString extends AbstractUnicodeString
 
     public function __wakeup()
     {
+        if (!\is_string($this->string)) {
+            throw new \BadMethodCallException('Cannot unserialize '.__CLASS__);
+        }
+
         normalizer_is_normalized($this->string) ?: $this->string = normalizer_normalize($this->string);
     }