[6.x] Pass the exception to the rescue closure

[SjorsO]

I'm using the rescue helper to make sure a fragile part of my application can't cause a crash. I'm storing both the error message and the object to make debugging easier. The problem is that when using the rescue helper, i can only see the real exception in my logs, and i can't store it in the database.

Currently:

[$error, $object] = rescue(function () use ($file) {
    return [null, new SomeFragileObject($file)];
}, ['An exception was thrown', null]);

With this PR i can do this:

[$error, $object] = rescue(function () use ($file) {
    return [null, new SomeFragileObject($file)];
}, function ($e) {
    // $e can be a custom exception with a detailed error message
    return [$e->getMessage(), null];
});