Merge branch '4.3' into 4.4

* 4.3:
  Fix inconsistent return points.
  pass translation parameters to the trans filter
  [Mime] fixed wrong mimetype
  [ProxyManagerBridge] Polyfill for unmaintained version
  [HttpClient] Declare `$active` first to prevent weird issue
  Remove deprecated assertContains
  [HttpClient] fix tests
  SCA: dropped unused mocks, duplicate import and a function alias usage
  Added correct plural for box -> boxes
  [Config] fix test
  Fix remaining tests
  Improve fa (persian) translation

Author: nicolas-grekas

Loader/XmlFileLoader.php

@@ -331,7 +331,7 @@ private function parseConfigs(\DOMElement $node, string $path)
     private function parseDefaultsConfig(\DOMElement $element, string $path)
     {
         if ($this->isElementValueNull($element)) {
-            return;
+            return null;
         }
 
         // Check for existing element nodes in the default element. There can
@@ -365,7 +365,7 @@ private function parseDefaultsConfig(\DOMElement $element, string $path)
     private function parseDefaultNode(\DOMElement $node, string $path)
     {
         if ($this->isElementValueNull($node)) {
-            return;
+            return null;
         }
 
         switch ($node->localName) {