Big ugly errors displayed when a new user is in Querki

(Bug, Closed -> Fixed, Priority: Critical, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Summary: See Details; found by Ailis.
As reported by her:
And on multiple pages, I’m getting what’s shown in the attached picture - errors down the right margin of the window. I’m seeing this on desktop Safari on a Mac, but not on mobile Safari on my phone.
3y284n2/c64eadcc39fa67d3cbad2782da80bbf901afae23.jpg