website_twitter: authentication error popup with proper description base on twitter error code and responses

<b>Purpose:</b> For getting proper error message (If user enter invalid API key or secret, tweet is protected  can not getting tweets, Invalid Authorization, Something is misconfiguration)

<b>Task:</b> https://www.odoo.com/web#id=8677&view_type=form&model=project.task&menu_id=3942&action=327
<b>Pad:</b> https://pad.odoo.com/p/r.O5ZH6hmk5EQokj5t
Hello , I need help. I'm define all error code and error message into <code>TWITTER_EXCEPTION</code> dictionary in top of the page. 
And line 46 to check error code exist in <code>TWITTER_EXCEPTION</code> dictionary and return relevant error code message.

But If ii'm define constants, variable name can't define as error code (integer value).