Runtime error with Ember CLI 0.2.5 about ember-cli-google-analytics HOT 5 OPEN

There was an error running your app in fastboot. More info about the error: 
 TypeError: window[globalVariable] is not a function
    at Class.pageviewToGA (/sitepath/tmp/broccoli_merge_trees-output_path-0o3SJA8u.tmp/assets/ew/mixins/google-pageview.js:22:1)
    at Object.applyStr (/sitepath/tmp/broccoli_merge_trees-output_path-0o3SJA8u.tmp/assets/vendor/ember/ember.debug.js:45470:1)
    at sendEvent (/sitepath/tmp/broccoli_merge_trees-output_path-0o3SJA8u.tmp/assets/vendor/ember/ember.debug.js:22871:1)
    at Class.trigger (/sitepath/tmp/broccoli_merge_trees-output_path-0o3SJA8u.tmp/assets/vendor/ember/ember.debug.js:38519:1)
    at invokeWithOnError (/sitepath/tmp/broccoli_merge_trees-output_path-0o3SJA8u.tmp/assets/vendor/ember/ember.debug.js:9035:1)
    at Queue.flush (/sitepath/tmp/broccoli_merge_trees-output_path-0o3SJA8u.tmp/assets/vendor/ember/ember.debug.js:8923:1)
    at DeferredActionQueues.flush (/sitepath/tmp/broccoli_merge_trees-output_path-0o3SJA8u.tmp/assets/vendor/ember/ember.debug.js:9086:1)
    at Backburner.end (/sitepath/tmp/broccoli_merge_trees-output_path-0o3SJA8u.tmp/assets/vendor/ember/ember.debug.js:9165:1)
    at Timeout.Backburner._boundAutorunEnd [as _onTimeout] (/sitepath/tmp/broccoli_merge_trees-output_path-0o3SJA8u.tmp/assets/vendor/ember/ember.debug.js:9134:1)
    at ontimeout (timers.js:365:14)
    at tryOnTimeout (timers.js:237:5)
    at Timer.listOnTimeout (timers.js:207:5)

import Ember from 'ember';
import config from './config/environment';
import OtherMixin from 'other-mixin';
import googlePageview from './mixins/google-pageview';

let routerData = {
	location: config.locationType,
	rootURL: config.rootURL
};

let Router;
if ('ga' in window) {
	// Only add GA tracking if it's available (e.g. we're not using FastBoot)
	Router = Ember.Router.extend(OtherMixin, googlePageview, routerData);
} else {
	Router = Ember.Router.extend(OtherMixin, routerData);
}

Router.map(function() {
	// ... 
});

export default Router;