issue 37 Server Side Validator apply core code

git-svn-id: http://xe-core.googlecode.com/svn/branches/1.5.0@8477 201d5d3c-b55e-5fd7-737f-ddc643e51545

classes/context/Context.class.php

@@ -925,6 +925,8 @@ class Context {
 	 **/
 	function get($key) {
 		is_a($this,'Context')?$self=&$this:$self=&Context::getInstance();
+
+		if(!isset($self->context->{$key})) return null;
 		return $self->context->{$key};
 	}