JS SDK: Error: dropbox.js loaded in an unsupported JavaScript environment.

Hi,

I am developing a firefox extension. Here, I have tried to use dropbox datastore as storage. I am not able to load JS SDK in firefox extension. Reference extension is https://github.com/cgav/dropbox-firefox-extension

I am getting the following error in console.

console.error: firefox-extension:
Message: Error: dropbox.js loaded in an unsupported JavaScript environment.
Stack:
Resource://jid1-rpqb40q3z1iksq-at-jetpack/nekt/lib/tplib/dropbox-datastores-1.2-latest.js:2:1114
@resource://jid1-rpqb40q3z1iksq-at-jetpack/nekt/lib/tplib/dropbox-datastores-1.2-latest.js:2:1
CuddlefishLoader/options<.load@resource://gre/modules/commonjs/sdk/loader/cuddlefish.js:129:18
initDropbox@resource://jid1-rpqb40q3z1iksq-at-jetpack/nekt/lib/background.js:81:17
Background@resource://jid1-rpqb40q3z1iksq-at-jetpack/nekt/lib/background.js:112:2
@resource://jid1-rpqb40q3z1iksq-at-jetpack/nekt/lib/background.js:121:18
CuddlefishLoader/options<.load@resource://gre/modules/commonjs/sdk/loader/cuddlefish.js:129:18
run@resource://gre/modules/commonjs/sdk/addon/runner.js:145:19
startup/</<@resource://gre/modules/commonjs/sdk/addon/runner.js:86:7
Handler.prototype.process@resource://gre/modules/Promise-backend.js:870:23
this.PromiseWalker.walkerLoop@resource://gre/modules/Promise-backend.js:749:7
this.PromiseWalker.scheduleWalkerLoop/<@resource://gre/modules/Promise-backend.js:691:37