as a logged in user on any page in http://en.wikipedia.beta.wmflabs.org/

edit a page and attempt to save.

Save your changes interface shows "Error: unknown error"

fatal.log shows

[2014-06-18 16:18:37] Fatal error: Call to a member function getDisplayTitle() on a non-object at /srv/common-local/php-master/extensions/VisualEditor/ApiVisualEditorEdit.php on line 120
Server: deployment-apache01
Method: POST
URL: http://en.wikipedia.beta.wmflabs.org/w/api.php
Cookie: enwiki-gettingStartedUserId=kJSYCjZCvJa3o9xl48ODXiGk1DaduG2m; centralauth_LoggedOut=1402329725; ve-beta-welcome-dialog=1; optin=beta; centralnotice_bucket=0-4.2; edittoolscharsubset=0; GeoIP=US:Tucson:32.2217:-110.9265:v4; uls-previous-languages=%5B%22en%22%5D; mediaWiki.user.sessionId=2vKzOP6dVykMZfazhyIC7OKY5jkC0O3t; enwikiUserID=54; enwikiUserName=Cmcmahon; enwikiSession=29dd771993d2f54b0eb86b9ccc4e85df; centralauth_User=Cmcmahon; centralauth_Session=caf75694c6a3d741ef094fac43c50f47
Backtrace:
#0 /srv/common-local/php-master/extensions/VisualEditor/ApiVisualEditorEdit.php(120): ApiVisualEditorEdit::execute()
#1 /srv/common-local/php-master/includes/api/ApiMain.php(908): ApiVisualEditorEdit->execute()
#2 /srv/common-local/php-master/includes/api/ApiMain.php(363): ApiMain->executeAction()
#3 /srv/common-local/php-master/includes/api/ApiMain.php(334): ApiMain->executeActionWithErrorHandling()
#4 /srv/common-local/php-master/api.php(85): ApiMain->execute()
#5 /srv/common-local/w/api.php(3): require('/srv/common-loc...')
#6 {main}

Version: unspecified
Severity: major
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=66717