To be able to throw an exception when a session key is not found

[khalyomede]

Description

When a user tries to get a session by its key, and this key is not set, I should raise an meaningful error.

Expected behavior

To be able to set the key in the error as following:

use Folded\Exceptions\SessionKeyNotFoundException;

$exception = SessionKeyNotFoundException("key foo not found");
$exception->setKey("foo");

echo $exception->getKey(); // "foo"

Actual behavior

No exception to raise in this case.

Alternatives solutions

Raising an OutOfRangeException for now.

Notes