Executing "partials/svg/twitter.svg" at <.size>: can't evaluate field size in type *hugolib.pageState

I’m trying to use Hugo’s theme (gohugoioTheme) and I’m running into issues when trying to build the site. Specifically, I hit the error in my title when running hugo server. I haven’t modified the code here; it’s straight from the repo.

The line in partials\svg\twitter.svg is: svg{{ with .size }} height="{{ . }}" {{ end }}id=“Layer_1” style=“enable-background:new 0 0 67 67;” version=“1.1” viewBox=“0 0 67 67” width="{{ .size }}" xml:space=“preserve” xmlns=“http://www.w3.org/2000/svg” xmlns:xlink=“http://www.w3.org/1999/xlink”>`

What’s the error?