Giving empty "to_name" and "to_email" parameters during e-mail sending results in Fatal Error

I recently had a case, when I was sending a e-mail to subscribers, but each of them had either email or user id filled-in.

I used following code:

$send_params = Array ();
$send_params['to_name'] = $email;
$send_params['to_email'] = $email;
$this->Application->EmailEventUser('EVENT.NAME', $user_id, $send_params);

And I've discovered a bug, that when user have $id, but not e-mail empty recipient is added resulting Fatal Error during e-mail sending.