ANG-5236: Add node null check on IntegerPicker

Fixing: http://jira2.lgsvl.com/browse/ANG-5236

The node can be null when value is out of range.

DCO-1.1-Signed-Off-By: Kunmyon Choi <kunmyon.choi@lge.com>
Merge pull request #1221 from enyojs/ANG-5236-kunmyonchoi

ANG-5236: Add node null check on IntegerPicker