Session_destroy() returns error

Question

I am making a page, and in parts, PHP use, but in one part gives an error in the log out. Follow the error:

Warning: session_destroy(): Trying to Destroy uninitialized Session on line 22.

Follows the line:

if ((!$loginrequired) or ((isset($_SESSION) or !isset($_SESSION) and session_start()) 
    and (isset($_SESSION['lname']) and isset($_SESSION['lpass'])) 
    and isValidLogin($_SESSION['lname'], $_SESSION['lpass']))) {

    header("location:/questions/home");
} else {
    unset($_SESSION['lpass']);
    unset($_SESSION['lname']);
    if (isset($_SESSION)) {
        session_destroy();
    }
}

I thought it strange the error appeared, if I made the check.
Does anyone know what it can be?

Answer 1

Use like this:

session_start();
if (isset($_SESSION)) {
    session_destroy();
}