isset/required validation bug

[eluser]mjijackson[/eluser]
This bug is discussed on this thread. In that thread, some users found a clever workaround for what is actually a bug in the code. When validation runs, it short-circuits any fields that have an 'isset' or 'required' rule if they are in fact not set. However, in the short-circuit, it neglects to set the error message for that field. This can be remedied with the following:

Code:

$error = $field . '_error';
$this->$error = $message;

It's keeping the code behavior consistent throughout the Validation class. The code should be changed around line 232 of Validation.php in order to squash the bug.