Merge branch '6.3' into 6.4

* 6.3:
  Sync .github/expected-missing-return-types.diff
  [FrameworkBundle] Add void return-type to ErrorLoggerCompilerPass
  [DoctrineBridge] Fix cross-versions compat
  [HttpKernel] Handle nullable callback of StreamedResponse
  [Mailer] Capitalize sender header for Mailgun
  [FrameworkBundle] Configure `logger` as error logger if the Monolog Bundle is not registered
  DX: PHP CS Fixer - drop explicit nullable_type_declaration_for_default_null_value config, as it's part of ruleset anyway
  DX: PHP CS Fixer - drop explicit no_superfluous_phpdoc_tags config, as it's part of ruleset already
  Revert "Add keyword `dev` to leverage composer hint"
  [Validator] Add missing Ukrainian translations #51960
  [Validator] Add missing translations for Indonesian (id)
  [Validator] Add missing translations for Vietnamese (VI)
  Add missing Validator translations - Croatian (hr)
  Run high-deps tests with ORM 3 and DBAL 4
  [FrameworkBundle] Fix calling Kernel::warmUp() when running cache:warmup

Author: nicolas-grekas

StreamedResponse.php

@@ -56,8 +56,12 @@ public function setCallback(callable $callback): static
         return $this;
     }
 
-    public function getCallback(): \Closure
+    public function getCallback(): ?\Closure
     {
+        if (!isset($this->callback)) {
+            return null;
+        }
+
         return ($this->callback)(...);
     }