Return 404 error for pages that don't exist

htdocs/index.php

@@ -147,6 +147,7 @@ if (file_exists($comppath)) {
 	$compoutput = ob_get_contents();
 	ob_end_clean();
 } else {
+	header("HTTP/1.1 404 Not Found");
 	$smarty->assign("body", "Component ".$component['component']." not found");
 }