Symfony version(s) affected

all

Description

Related to #45205 issue, which was ignored...

When an exception is thrown in a kernel.terminate event,

• kernel.exception is thrown
• the Symfony ErrorListener::onKernelException handler the exception
• $response = $event->getKernel()->handle($request, HttpKernelInterface::SUB_REQUEST, false); is called
• this trigger the ErrorController and then the TwigErrorRenderer

1. The response rendered seems useless since the response was already sent before the terminate event. (cf https://symfony.com/doc/current/components/http_kernel.html#8-the-kernel-terminate-event)
2. It can produce extra-useless exception, in my case I have a custom view TwigBundle/Exception/error.html.twig
   which use the session and/or flashbag and I'm getting some Failed to start the session because headers have already been sent.

Introducing a kernel.terminate_exception and using it instead of kernel.exception could even appear as a BC break for kernel.exception listeners or a bugfix because according to the schema in the doc https://symfony.com/doc/current/components/http_kernel.html#handling-exceptions-the-kernel-exception-event, we can see the order Exception -> Response -> Terminate.

How to reproduce

• Throw an exception in a kernel.terminate listener -> You'll get extra code executed for no reason
• Add app.session.flashbag.get('success') call in a custom TwigBundle/Exception/error.html.twig template. -> You'll get failed to start the session error in your logs.

Possible Solution

Either throw a different event for exception thrown after the terminate exception

Either, at least provide a ExceptionEvent::isTerminated or TerminableInterface::isTerminated, which would allow to write

if ($thing->isTerminated()) {
     return;
}

at the beginning of some ExceptionListener like the ErrorListener

Additional Context

No response