/usr/lib/R/site-library/crosstalk/lib/bootstrap/js/bootstrap.js is in r-cran-crosstalk 1.0.0+dfsg-1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/R/site-library/crosstalk/lib/bootstrap/js/../../../../../../../share/javascript/bootstrap/js/bootstrap.js