I've tried several times, on different wikis, logged-in and as anonymous user, with RevisionSlider pinned and unpinned, but I was not able to reproduce the error. I was using Windows 10 and tested with Internet Explorer 11. See the screenshot for the exact version.

Everything worked as expected, and no errors popped up in the console (beside the usual warnings). See screenshot.

@Umherirrender could you please check again? We've deployed some patches since you filed the bug (none specific to Internet Explorer though), but maybe one of them fixed your problem as well. If not, could you provide a screenshot of the page including what's printed in the error console? Also, in what state is the RevisionSlider when it breaks - does it expand or still remain in collapsed state? Does it probably still work despite the error is shown, or does clicking/dragging revisions not work? Are more errors printed to the console when you continue interacting with the RevisionSlider?
Thank you for your report!

It works now, thanks for the re-testing

Just for the record: It was not expanding, so it stay on the collapsed state, after the error there was no more interactive possible