Don't terminate script execution when parsed template doesn't exist

and parse was called with 3rd argument = false.

program/include/rcube_output_html.php

@@ -400,7 +400,7 @@ class rcube_output_html extends rcube_output
                 'line' => __LINE__,
                 'file' => __FILE__,
                 'message' => 'Error loading template for '.$realname
-                ), true, true);
+                ), true, $write);
             return false;
         }