error in devtools on question pages: "unable to find or generate popover element"

I'm getting this in the devtools on question pages.

stacks.min.js?v=79a2fd33ef4b:1 Error connecting controller

'unable to find or generate popover element'

{identifier: 's-popover', controller: t, element: button.js-close-question-link.s-btn.s-btn__link.js-gps-track}
controller: t {context: D, popoverSelectorAttribute: 'aria-controls', referenceElement: button.js-close-question-link.s-btn.s-btn__link.js-gps-track}
element: button.js-close-question-link.s-btn.s-btn__link.js-gps-track
identifier: "s-popover"
[[Prototype]]: Object

Not sure what the significance of this is. The site's relatively new hover tooltip is working for the close link/button for me (the one that says "Vote to close this question (when closed, no new answers can be added)").