list: remove annoying error msg on select

list: remove annoying error msg on select

Summary:
on select below message was shown,

ERR<19329>: elm_main.c:1556 elm_object_widget_check() safety check failed: obj == NULL

Test Plan:
1. terminology -> options -> keys -> select item -> check error message
2. elementary_test -> list2 -> select topmost item -> check error message

Reviewers: raster, cedric, seoz, Hermet

Reviewed By: Hermet

Subscribers: seoz

Differential Revision: https://phab.enlightenment.org/D1185