Chrome Extension breaks Google Sheets - google-chrome-extension

Question

I'm working on a chrome extension to log analytics for my use of Google Drive. I've used a webNavigation.onCompleted.addListener function to send analytics a page view, and it all works properly, except when it comes to sheets.
I'm gettting an intermittent failure to load sheets properly. However, nothing logs in the extension's console as an error - it shows everything is working properly. In the console for the sheet I'm trying to load, I'm getting two strange errors popping up.
The first (in all its glory) is:
Uncaught TypeError: Cannot read property 'setTimeout' of undefined
Mfb # 2046562200-ritz_waffle_i18n_core.js:2745
pN # 2046562200-ritz_waffle_i18n_core.js:2746
ggb # 2046562200-ritz_waffle_i18n_core.js:2757
fxb # 2046562200-ritz_waffle_i18n_core.js:3558
r.load # 2046562200-ritz_waffle_i18n_core.js:3555
loadWaffle # edit:163
w2b # ritz-0.js:1465
KGb # ritz-0.js:990
g # ritz-0.js:2
jC # ritz-0.js:649
mC # ritz-0.js:652
(anonymous function) # ritz-0.js:651
AGb # ritz-0.js:3
(anonymous function) # ritz-0.js:7622
(anonymous function) # VM3274:1
m # edit:110
(anonymous function) # edit:111
d # edit:107
(anonymous function) # edit:108
And the second is:
Uncaught TypeError: Cannot read property 'Yu' of undefined
r.jLa # 2046562200-ritz_waffle_i18n_core.js:361
I'm having trouble understanding what's creating this problem. My code isn't modifying any headers, and only triggers once web navigation is complete. Here's the function that seems to be causing this issue:
chrome.webNavigation.onCompleted.addListener(
// callback
function(info) {
console.log("webNavigation Complete - Docs");
console.log(info.url);
var fields = { hitType:'pageview'};
chrome.pageAction.show(info.tabId);
// check for editor of docs, sheets, slides, etc.
if (info.url.indexOf('docs') > -1 && info.url.indexOf('/d/') > -1) {
var start = info.url.indexOf('.com/')+5;
var end = info.url.indexOf('/',start+1);
var type = info.url.substring(start,end);
start = end+2;
end = info.url.indexOf('/',start+1);
var docId = info.url.substring(start,end);
fields['page'] = docId;
ga('send','event',type,'Load');
}
// check for editor of docs, sheets, slides, etc.
if (info.url.indexOf('macros') > -1 && info.url.indexOf('/d/') > -1) {
console.log('Apps-Script');
ga('send','event',type,'Apps-Script');
}
if (info.url.indexOf('drive') > -1 ){
fields['page'] = '/drive';
}
if (fields.page) {
var tabId = info.tabId;
chrome.pageAction.show(tabId);
chrome.tabs.get(tabId,function(tab) {
fields['title'] = tab.title;
console.log(fields);
//ga('send',fields);
});
}
},
//filters
{url:[{hostContains:'docs.google.com'},
{hostContains:'drive.google.com'}]
});