[web/views] Fix exception in CWProperty edit form (closes #5087412) Also add missing help message. The overall display is ugly, but at least the message is shown.

etc/init.d
etc/cubicweb.d
etc/bash_completion.d
usr/bin
usr/share/doc/cubicweb-ctl
var/log/cubicweb
var/lib/cubicweb/backup
var/lib/cubicweb/instances