Npm pack https://github.com/jawj/OverlappingMarkerSpiderfier
This module uses the already compiled and minimized js library.
After importing this package, it populates the Spiderifier class to
window.OverlappingMarkerSpiderfier.
That's not so nice, however the solution should provided in the upsream package. This is only a very thin wrapper. See discussion here: https://github.com/jawj/OverlappingMarkerSpiderfier/issues/125