office365 - Office 365 Web Add-in: Office.initialize() is not being called -

i have assigned office.initialize function initialize outlook add-in it's never called , verified using console.log() statements. when opened developer console, got error 'uncaught typeerror: cannot redefine property: context" (refer screenshot). runtime error happens 75% of time never happened week ago.

could transient error?

i'm using chrome 51.0.2704.106 , office 365's outlook (web app).

this error fault. accidentally referenced outlook's javascript file (ie: <script src="https://appsforoffice.microsoft.com/lib/1/hosted/office.js" type="text/javascript"></script>) twice. after removing 1 of references, error disappeared.