I suggest that starting from Symfony 7.0 the HttpKernel will start to catch \Throwable and convert them to a Response.

This was first asked in #16205, I face a similar issue with Runtime component and Bref..

The reason I push for this change is to embrace the request/response workflow of the Kernel without trusting the custom error handler. In an environment where you serve multiple requests with the same PHP process (read: RoadRunner, Swoole, Bref) you would write something like:

$kernel = new Kernel('prod', false);
while (true) {
  $request = /* create sf request from custom environment */
  try {
    $response = $kernel->handle(request);
    return ResponseConverter::convert($response);
  } catch (\Throwable $e) {
    exit(1);
  }
}

(pseudo code of course. Here is a real example)

The exit(1) means a hard crash. For Bref Runtime it would result in a 500 error from API-gateway. Since the \Throwable is caught, the Symfony error handler is not used. If we would not to catch the \Throwable, then the Symfony error handler would be used, but it would print a Response instead of returning it. (Printing a response will just add HTML on the CLI...)

Other PRs and issues related to this:

• #45301
• #26514
• #22128
• #36885
• #25467

I'm happy to let the HttpKernel to catch the \Throwable exception right now, but I thought this very conservative PR would have a higher change to get merged.

Also note that we do not specify any behaviour on our HttpKernelInterface