Hi all,
It turns out mozjs60 60.2.0 (in F29 updates-testing and rawhide)
silently broke ABI and that broke gjs that gnome-shell uses. I've
rebuilt gjs; if you've already updated and can't log in, then
gjs-1.54.0-3.fc29 and gjs-1.54.0-3.fc30 should help.
https://bodhi.fedoraproject.org/updates/FEDORA-2018-bc166c0e29 has the
rebuilt gjs.
Hope this helps someone,
Kalev