After uninstalling Firefox I did look at Vivaldi, but went with Maxthon: http://maxthon.com. It's available for Linux and all major platforms. Fast too.
https://github.com/segmentio/analytics.js/issues/501
I'm the reporter there. Same user on Firefox (natch) doesn't cause the same errors. I also don't see those errors from any other browser. It's always Maxthon.