Merge branch '5.4' into 6.2

* 5.4:
  Avoid call on null
  [Notifier] Document Firebase options object in readme
  [ErrorHandler] Fix sending Vary header with SerializerErrorRenderer
  Fix intl data tests
  [DoctrineBridge] fix issue with missing stopwatch events
  [HttpClient] Fix canceling MockResponse

Author: nicolas-grekas

Response/MockResponse.php

@@ -106,7 +106,7 @@ public function cancel(): void
         }
 
         $onProgress = $this->requestOptions['on_progress'] ?? static function () {};
-        $dlSize = isset($this->headers['content-encoding']) || 'HEAD' === $this->info['http_method'] || \in_array($this->info['http_code'], [204, 304], true) ? 0 : (int) ($this->headers['content-length'][0] ?? 0);
+        $dlSize = isset($this->headers['content-encoding']) || 'HEAD' === ($this->info['http_method'] ?? null) || \in_array($this->info['http_code'], [204, 304], true) ? 0 : (int) ($this->headers['content-length'][0] ?? 0);
         $onProgress($this->offset, $dlSize, $this->info);
     }
 

Tests/MockHttpClientTest.php

@@ -544,7 +544,7 @@ public function testResetsRequestCount()
         $this->assertSame(0, $client->getRequestsCount());
     }
 
-    public function testCancellingMockResponseExecutesOnProgressWithUpdatedInfo()
+    public function testCancelingMockResponseExecutesOnProgressWithUpdatedInfo()
     {
         $client = new MockHttpClient(new MockResponse(['foo', 'bar', 'ccc']));
         $canceled = false;

Tests/Response/MockResponseTest.php

@@ -118,6 +118,14 @@ public function testErrorIsTakenIntoAccountInInitialization()
         ]))->getStatusCode();
     }
 
+    public function testCancelingAMockResponseNotIssuedByMockHttpClient()
+    {
+        $mockResponse = new MockResponse();
+        $mockResponse->cancel();
+
+        $this->assertTrue($mockResponse->getInfo('canceled'));
+    }
+
     public function testMustBeIssuedByMockHttpClient()
     {
         $this->expectException(InvalidArgumentException::class);