If some files lost in /var/db/pkg/<port>/ after system crash f.e.,

If some files lost in /var/db/pkg/<port>/ after system crash f.e.,
pkg_manage silently dumps core, pkg_info claims about them to
stderr, which makes very difficult to find what directory cause it via
tons of pkg_info -a output. I found solution which covers both variants,
now pkg_info claims about missing files to stdout among valid output
with ERROR: prefix. It heals pkg_manage to not dump core and makes
easy to find errors in pkg_info -a output by simple /ERROR 'more' command.