unbreak typeaheads for /owners/new

Summary:
D6057 introduced images in the typeahead results, but not all
projects return a valid result. This silently broke /owners/new because
the exception "Call to a member function loadProfileImageURI() on a non-object"
is swallowed somewhere in the handler.

Test Plan: go to /owners/new and type something in the primary owner field

Reviewers: epriestley, nh, Afaque_Hussain

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D6245