Self-repair ran into issues in the past where users with privacy addons that clear localStorage would see a survey multiple times if the survey had a high sample rate. To avoid this, they wrote a value to localStorage for all users, and then used that as a flag to check whether the user has since cleared localStorage. The downside to this plan is that it excludes new users. Until the addon lands (which will use a different storage mechanism besides localStorage), we might want to do something similar in case we run a survey with a high sampling rate before the addon hits release.

https://github.com/mozilla/self-repair-server/pull/212 was my solution and discussion originally.

I suspect we won't implement and ship this before the system add-on lands, and I don't think we're likely to run into this specific error case before then anyway, so I think we should WONTFIX this.