Symfony version(s) affected: 4.2.x

Description
HttpException and all its descendants do not allow \Error as $previous argument and raise a TypeError by itself. This is quite weird, as those cases have to be handled separately and cannot be handled with a generic \Throwable catch block.

❓ I could imagine this has been forgotten in the PHP 7.x transition?

How to reproduce

try {
    throw new class ("arbitrary error") extends \Error {};
} catch (\Throwable $err) {
    throw new \Symfony\Component\HttpKernel\Exception\HttpException(500, 'An unsuspected error occurred.', $err);
}

Possible Solution
Change signature of HttpException to hint \Throwable instead of \Exception for $previous as defined in \Exception.