[EventDispatcher] Incorrect error reported when arguments to dispatch() are swapped #34676
Description
Symfony version(s) affected: 4.4.0
Description
The EventDispatcherInterface currently allows dispatching event by its name only (dispatch($eventName)) or by supplying the event and its name (dispatch($event, $eventName)).
In the second case, when the arguments are swapped, an incorrect error will be returned in some cases. Specifically, it will be incorrect when the event will be a subclass of Symfony\Contracts\EventDispatcher\Event as opposed to a subclass of Symfony\Component\EventDispatcher\Event (the latter has been deprecated since 4.3).
How to reproduce
Attempt to dispatch an event that is a subclass of Symfony\Contracts\EventDispatcher\Event and swap the arguments (provide event name first, its object second).
Possible Solution
The line in
Additional context
This issue is only valid for the 4.4 branch (and maybe 4.3?). In 5.0, EventDispatcher doesn't contain the code in question.