I've installed mbserver and postgresql on my local machine by following the instructions provided in INSTALL.md. I created a clean database (carton exec ./admin/InitDb.pl – --createdb --clean) and started the server.
Then I tried to create a new user; however, I was presented with the following error:

Caught exception in MusicBrainz::Server::Controller::Account->register "DBD::Pg::st execute failed: ERROR: insert or update on table "editor_watch_release_group_type" violates foreign key constraint "editor_watch_release_group_type_fk_release_group_type"
DETAIL: Key (release_group_type)=(2) is not present in table "release_group_primary_type".

(see full error log)

mbserver git commit id: f862b74455551ef66831582eb303941bbeed6173