Merge branch '6.4' into 7.0

* 6.4:
  More short closures + isset instead of null checks + etc.

Author: nicolas-grekas

Matcher/Dumper/CompiledUrlMatcherDumper.php

@@ -346,7 +346,7 @@ private function compileDynamicRoutes(RouteCollection $collection, bool $matchHo
             $state->markTail = 0;
 
             // if the regex is too large, throw a signaling exception to recompute with smaller chunk size
-            set_error_handler(function ($type, $message) { throw str_contains($message, $this->signalingException->getMessage()) ? $this->signalingException : new \ErrorException($message); });
+            set_error_handler(fn ($type, $message) => throw str_contains($message, $this->signalingException->getMessage()) ? $this->signalingException : new \ErrorException($message));
             try {
                 preg_match($state->regex, '');
             } finally {

Router.php

@@ -180,10 +180,10 @@ public function setContext(RequestContext $context): void
     {
         $this->context = $context;
 
-        if (null !== $this->matcher) {
+        if (isset($this->matcher)) {
             $this->getMatcher()->setContext($context);
         }
-        if (null !== $this->generator) {
+        if (isset($this->generator)) {
             $this->getGenerator()->setContext($context);
         }
     }
@@ -227,7 +227,7 @@ public function matchRequest(Request $request): array
      */
     public function getMatcher(): UrlMatcherInterface|RequestMatcherInterface
     {
-        if (null !== $this->matcher) {
+        if (isset($this->matcher)) {
             return $this->matcher;
         }
 
@@ -268,7 +268,7 @@ function (ConfigCacheInterface $cache) {
      */
     public function getGenerator(): UrlGeneratorInterface
     {
-        if (null !== $this->generator) {
+        if (isset($this->generator)) {
             return $this->generator;
         }