Hello Susobh,
You are trying to backport something that we fixed in GAS 2.50.
GWC HTML5 first implementation has been released in GAS 2.41. We are fixing issues for GWC-HTML5 in GAS 2.50 trunck.
GAS 2.50 is compatible with your FGLGWS 2.41, therefore please update your GAS to the latest version 2.50.xx.
In this update you do not have to recompile your application, just update the GAS to 2.50.
Best regards,
Olivier from Four Js Support