Uncaught ReferenceError: _paq is not defined

[Simran-B]

I'm constantly getting this error in the dev console in Chrome, using Gitbook 2 as well as 3:

Uncaught ReferenceError: _paq is not defined
    at Object.<anonymous> (plugin.js:7)
    at Object.dispatch (app.js:4436)
    at Object.elemData.handle (app.js:4122)
    at Object.trigger (app.js:4351)
    at Object.<anonymous> (app.js:4902)
    at Function.each (app.js:375)
    at jQuery.fn.init.each (app.js:140)
    at jQuery.fn.init.trigger (app.js:4901)
    at Object.notifyPageChange [as notify] (app.js:24586)
    at Object.start (app.js:24406)

Live demo: https://docs.arangodb.com/3.1/Manual/

paq is declared as var _paq = _paq || []; in the template, whereas the offending line is part of the plugin.js. Since paq is not a global variable (window._paq), I wonder how this is supposed to work.