What are the best practices for handling session variables in PHP to avoid errors like the ones mentioned in the thread?

Session variables in PHP should be properly initialized and checked for existence before using them to avoid errors. One common practice is to use isset() or empty() functions to check if a session variable is set before accessing its value. Additionally, it's important to start the session at the beginning of each script where session variables are used and to properly unset or destroy session variables when they are no longer needed.

session_start();

// Check if a session variable is set before using it
if(isset($_SESSION['username'])) {
    $username = $_SESSION['username'];
    // Use $username safely
} else {
    // Handle the case where the session variable is not set
}

// Unset or destroy session variables when they are no longer needed
unset($_SESSION['username']);
// or
session_unset();
// or
session_destroy();