Merge branch '6.0' into 6.1

* 6.0:
  [Translation] Fix Crowdin documentation urls
  ignore missing keys when mapping DateTime objects to uninitialized arrays
  fix writes to static $kernel property
  [Notifier] Fix test logic
  [Validator] Hint that `egulias/email-validator` needs to be installed for strict mode as default config

Author: xabbuh

Constraints/EmailValidator.php

@@ -70,6 +70,10 @@ public function validate(mixed $value, Constraint $constraint)
         }
 
         if (null === $constraint->mode) {
+            if (Email::VALIDATION_MODE_STRICT === $this->defaultMode && !class_exists(EguliasEmailValidator::class)) {
+                throw new LogicException(sprintf('The "egulias/email-validator" component is required to make the "%s" constraint default to strict mode.', EguliasEmailValidator::class));
+            }
+
             $constraint->mode = $this->defaultMode;
         }