Fixed deprecation warnings about passing null as parameter

Author: derrabus

DependencyInjection/RegisterControllerArgumentLocatorsPass.php

@@ -124,7 +124,7 @@ public function process(ContainerBuilder $container)
                 $args = [];
                 foreach ($parameters as $p) {
                     /** @var \ReflectionParameter $p */
-                    $type = ltrim($target = ProxyHelper::getTypeHint($r, $p), '\\');
+                    $type = ltrim($target = (string) ProxyHelper::getTypeHint($r, $p), '\\');
                     $invalidBehavior = ContainerInterface::IGNORE_ON_INVALID_REFERENCE;
 
                     if (isset($arguments[$r->name][$p->name])) {

EventListener/RouterListener.php

@@ -164,7 +164,7 @@ public static function getSubscribedEvents()
     private function createWelcomeResponse(): Response
     {
         $version = Kernel::VERSION;
-        $projectDir = realpath($this->projectDir).\DIRECTORY_SEPARATOR;
+        $projectDir = realpath((string) $this->projectDir).\DIRECTORY_SEPARATOR;
         $docVersion = substr(Kernel::VERSION, 0, 3);
 
         ob_start();

Tests/HttpCache/HttpCacheTest.php

@@ -212,8 +212,8 @@ public function testIncrementsMaxAgeWhenNoDateIsSpecifiedEventWhenUsingETag()
 
     public function testValidatesPrivateResponsesCachedOnTheClient()
     {
-        $this->setNextResponse(200, [], '', function ($request, $response) {
-            $etags = preg_split('/\s*,\s*/', $request->headers->get('IF_NONE_MATCH'));
+        $this->setNextResponse(200, [], '', function (Request $request, $response) {
+            $etags = preg_split('/\s*,\s*/', $request->headers->get('IF_NONE_MATCH', ''));
             if ($request->cookies->has('authenticated')) {
                 $response->headers->set('Cache-Control', 'private, no-store');
                 $response->setETag('"private tag"');