Check mail is started (#1967)

* Check mail is started

* Fix CS

* Return type

---------

Co-authored-by: barryvdh <[email protected]>

Author: barryvdh

src/CollectorProviders/MailCollectorProvider.php

@@ -27,8 +27,15 @@ public function __invoke(Dispatcher $events, array $options): void
         if ($options['timeline'] ?? true) {
             $timeCollector = $this->debugbar->getTimeCollector();
 
-            $events->listen(MessageSending::class, fn(MessageSending $e) => $timeCollector->startMeasure('mail' . spl_object_id($e->message), 'Mail: ' . $e->message->getSubject()));
-            $events->listen(MessageSent::class, fn(MessageSent $e) => $timeCollector->stopMeasure('mail' . spl_object_id($e->message)));
+            $events->listen(MessageSending::class, fn(MessageSending $e) => $timeCollector->startMeasure('Mail: ' . $e->message->getSubject()));
+            $events->listen(MessageSent::class, function (MessageSent $e) use ($timeCollector): void {
+                $name = 'Mail: ' . $e->message->getSubject();
+                if ($timeCollector->hasStartedMeasure($name)) {
+                    $timeCollector->stopMeasure($name);
+                } else {
+                    $timeCollector->addMeasure($name);
+                }
+            });
         }
     }
 }