When attempting to add a tracklist to a release that contains no existing tracklist the error included below is thrown.

Steps to reproduce:

1. http://musicbrainz.org/release/054ef95a-d342-4b75-bd1a-4b8853df0f36/edit
2. Click 'Tracklist'

=======

Error:

Caught exception in MusicBrainz::Server::Controller::ReleaseEditor::Edit->edit "Can't call method "add_error" on an undefined value at /home/musicbrainz/musicbrainz-server/script/../lib/MusicBrainz/Server/Form/ReleaseEditor/Tracklist.pm line 234."
Stack trace:
line 234 MusicBrainz::Server::Form::ReleaseEditor::Tracklist
line 105 MusicBrainz::Server::Form
line 524 MusicBrainz::Server::Wizard
line 238 MusicBrainz::Server::Wizard
line 173 MusicBrainz::Server::Wizard
line 388 MusicBrainz::Server::Wizard
line 132 MusicBrainz::Server::Wizard
line 91 MusicBrainz::Server::Wizard::ReleaseEditor
line 17 MusicBrainz::Server::Controller::ReleaseEditor::Edit
line 258 MusicBrainz::Server
Request data:

$VAR1 = {
'query_parameters' => {},
'body_parameters' =>

{ 'artist_credit.names.0.name' => 'This Is the Kit', 'packaging_id' => '4', 'date.month' => '6', 'release_group_id' => '990296', 'labels.0.catalog_number' => 'DOCD14', 'release_group.name' => 'Wriggle Out the Restless', 'artist_credit.names.0.artist.id' => '376099', 'labels.0.deleted' => '0', 'country_id' => '221', 'labels.0.name' => 'Disco-Ordination Records', 'date.year' => '2011', 'script_id' => '28', 'status_id' => '1', 'step_tracklist' => 'Tracklist', 'date.day' => '19', 'name' => 'Wriggle Out The Restless (Remixes)', 'barcode' => '3661585924890', 'artist_credit.names.0.join_phrase' => '', 'labels.0.label_id' => '44286', 'wizard_session_id' => '0.372825348343817', 'language_id' => '120', 'comment' => '', 'gc-mode' => 'English', 'artist_credit.names.0.artist.name' => 'This Is the Kit', 'annotation' => '' }

};