bug #34677 [EventDispatcher] Better error reporting when arguments to dispatch() are swapped (rimas-kudelis)

This PR was squashed before being merged into the 4.3 branch.

Discussion
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[EventDispatcher] Better error reporting when arguments to dispatch() are swapped

| Q             | A
| ------------- | ---
| Branch?       | 4.3
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | Fix #34676
| License       | MIT

Incorrect error is currently being reported when the second argument is an instance of `Symfony\Contracts\EventDispatcher\Event`.

Commits
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54aac56 [EventDispatcher] Better error reporting when arguments to dispatch() are swapped

Author: nicolas-grekas

src/Symfony/Component/EventDispatcher/EventDispatcher.php

@@ -54,7 +54,7 @@ public function dispatch($event/*, string $eventName = null*/)
 
         if (\is_object($event)) {
             $eventName = $eventName ?? \get_class($event);
-        } elseif (\is_string($event) && (null === $eventName || $eventName instanceof Event)) {
+        } elseif (\is_string($event) && (null === $eventName || $eventName instanceof ContractsEvent || $eventName instanceof Event)) {
             @trigger_error(sprintf('Calling the "%s::dispatch()" method with the event name as the first argument is deprecated since Symfony 4.3, pass it as the second argument and provide the event object as the first argument instead.', EventDispatcherInterface::class), E_USER_DEPRECATED);
             $swap = $event;
             $event = $eventName ?? new Event();

src/Symfony/Component/EventDispatcher/LegacyEventDispatcherProxy.php

@@ -59,7 +59,7 @@ public function dispatch($event/*, string $eventName = null*/)
 
         if (\is_object($event)) {
             $eventName = $eventName ?? \get_class($event);
-        } elseif (\is_string($event) && (null === $eventName || $eventName instanceof Event)) {
+        } elseif (\is_string($event) && (null === $eventName || $eventName instanceof ContractsEvent || $eventName instanceof Event)) {
             @trigger_error(sprintf('Calling the "%s::dispatch()" method with the event name as the first argument is deprecated since Symfony 4.3, pass it as the second argument and provide the event object as the first argument instead.', ContractsEventDispatcherInterface::class), E_USER_DEPRECATED);
             $swap = $event;
             $event = $eventName ?? new Event();