Mark property error as deprecated

htdocs/core/class/commonobject.class.php

@@ -35,8 +35,18 @@
 abstract class CommonObject
 {
     public $db;
+
+    /**
+     * @var error 	Error string
+     * @deprecated	Use instead the array of error strings
+     */
     public $error;
+
+    /**
+     * @var errors	Aray of error string
+     */
     public $errors;
+
     public $canvas;                // Contains canvas name if it is
 
     public $name;