fixed error msg for DBG when executed by cli

SE/se-lib/DBG.php

@@ -3,15 +3,15 @@
 class DBG {
 
 	public static function isActive($mode = null) {
-		return true == V::get('_DBG_ON', false, $_SESSION);
+		return (isset($_SESSION)) ? (true == V::get('_DBG_ON', false, $_SESSION)) : false;
 	}
 
 	public static function activate($mode = null) {// @used in User::auth()
-		$_SESSION['_DBG_ON'] = true;
+		if (isset($_SESSION)) $_SESSION['_DBG_ON'] = true;
 	}
 
 	public static function deactivate($mode = 'all') {
-		$_SESSION['_DBG_ON'] = false;
+		if (isset($_SESSION)) $_SESSION['_DBG_ON'] = false;
 	}
 
 	/**