add guard against empty collections in DataList

Issue: CMB-3602
Enyo-DCO-1.1-Signed-off-by: Ryan Duffy (ryan.duffy@lge.com)
Merge pull request #923 from enyojs/CMB-3602-ryanjduffy

Fixes CMB-3602

Reviewed-By: Krishna Rangarajan (krishna.rangarajan@lge.com)
Integrated-By: Aaron Tam (aaron.tam@lge.com)