modules/prefs/elm_entry: Add safety check for NULL pointer and fix memory leak
modules/prefs/elm_entry: Add safety check for NULL pointer and fix memory leak

Summary: Add safety check for NULL pointer and fix memory leak

Reviewers: cedric, woohyun, Hermet, stefan_schmidt, raster

Reviewed By: stefan_schmidt, raster

Subscribers: Hermet

Differential Revision: https://phab.enlightenment.org/D2740

rvandegrift/elementary,tasn/elementary,tasn/elementary,rvandegrift/elementary,tasn/elementary,rvandegrift/elementary,tasn/elementary,rvandegrift/elementary,tasn/elementary