The bootstrap.min.js is missing under ~/ResourcePackages/Bootstrap/assets/dist/js/.
It had been renamed to project.min.js in Sitefinity CMS 10.0.6400.0 (upgraded from 9.0.6220.0).
Here are two workaround soultions:
Either updating the following code to
@Html.Script(Url.WidgetContent("Mvc/Scripts/Bootstrap/js/project.min.js"), "top", false)
in the following two files:
or just copying bootstrap.min.js under ~/ResourcePackages/Bootstrap/assets/dist/js/.
They should really remove this reference to bootstrap.js completely.
It is the only widget in feather that still calls this manually. If you want bootstrap js to work, rather include it via grunt. If you already included bootstrap.js in say, your layout/default.cshtml, then adding this widget to a page will break all bootstrap js functionality.