chgserver: catch RepoError while loading configuration
Recent share safe work introduced functionality to read share source config file
on dispatch. This can result in RepoError while reading config file as the
shared source might not be present.
`test-share.t#safe` was failing with chg earlier because of this.
Differential Revision: https://phab.mercurial-scm.org/D9462
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}